SMITHSONIAN CONTRIBUTIONS TO
BOTANY
NUMBER 5
Burrett Nelson R W ~ The Woods and Flora
of the Florida Keys:
cc Pinnatae”
SMITHSONIAN INSTITUTION PRESS
CITY OF WASHINGTON
1972
ABSTRACT
Barrett Nelson Rock. The Woods and Flora of the Florida Keys: “Pinnatae.” Smithsonian
Contributions to Botany, number 5, 35 pages, 35 figures, 1972.-The “Pinnatae,”
comprising six families of woody plants with pinnately compound leaves, is
represented on the Florida Keys by at least 16 species. The taxonomic treatment of
these families at the ordinal level has been inconsistent. The purpose of this study is
to correlate the data derived from intensive study of the xylem anatomy of these 16
species with data from the literature concerning these and other members of the
families involved, so that new insight might be gained concerning the taxonomic
relationships among these families.
This study indicates that the members of the Pinnatae are anatomically homogeneous.
All members possess simple perforation plates, vessel elements having alternate
intervascular pitting, fibrous elements with small slitlike simple to vestigially bordered
pits, and apotracheal and paratracheal axial parenchyma, or both. Secretory structures,
such as crystalliferous idioblasts, parenchymatous cells containing “gum,” and
intercellular canals, are of wide occurrence within the Pinnatae. In addition, many
species possess septate fibers and axial parenchyma arranged in aggregate patterns,
with banded arrangements being most frequent.
There is no anatomical basis for the separation of families into distinct orders in
my view. The only separation of families within the Pinnatae suggested by a syndrome
of several unique characters, in addition to those common to all members,
is the formation of an Anacardiaceae-Burseraceae complex. The members of the
Pinnatae belong to a taxon corresponding well with Cronquist’s Sapindales.
Phylogenetically, the Pinnatae constitutes an advanced taxon, based on xylem
anatomy.
(Scientific Article No. A1731, Contribution No. 4506, of the Maryland Agricultural Experiment
Station, Department of Botany.)
Oficial publication date is handstamped in a limited number of initial copies and is recorded
in the Institution’s annual report, Smithsonian Year.
UNITED STATES GOVERNMENT PRINTING OFFICE
WASHINGTON : 1972
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402 - Price 50 cents (paper cover)
Stock Number 4700-0152
Barrett Nelson ROC^ The Woods and Flora
Introduction
The Anacardiaceae, Burseraceae, Meliaceae, Rutaceae,
Sapindaceae, and Simaroubaceae constitute a
group of plant families comprising nearly 6,000
species of pantropical distribution. All are characterized
by plants with pinnately compound leaves.
These six families are represented on the Florida
Keys by at least 15 genera, each has a single species,
except for Zanthoxylum, which has two species there.
This investigation is an intensive study of the secondary
xylem of these plants (Table 1). According to
Brizicky (1962b, 1963)) Picramnia pentandra Swartz
(Simaroubaceae) , Melicoccus bijugatus (Sapindaceae)
, Amyris maritima Jacquin, Zanthoxylum coriaceum
A. Richard, and four naturalized species of
Citrus in addition to C. aurantiifolia (Rutaceae) are
also to be found on the Florida Keys but are not
included in this study. Of the plants studied, only
the familial affinity of the genus Suriana has been
seriously questioned. The assignment of the othzr
genera to families has been more or less generally
accepted. Small (1913) placed the genus Dodonaea
in his monogeneric Dodonaeaceae. My work has
been undertaken to correlate the data derived from
the Florida Keys members of these six families with
data obtained previously by earlier workers, with the
hope that the information gained, although based
on a limited number of genera, will give additional
insight on the taxonomic relationships of these plants.
The taxonomic usefulness of data derived from
study of the secondary xylem of dicotyledons, when
correlated with morphological, cytological, palyno-
Barrett Nelson Rock, Department of Botany, University of
Maryland, College Park, Maryland 20742.
of the Florida Keys:
6 6 Pinnatae”
logical, and other information has been widely acknowledged
(Chalk 1944, Heimsch 1942, Keck 1957,
Stern 1952, Tippo 1946, and others). Comparative
anatomical studies of the secondary xylem of some
or all of the genera treated in this investigation
(Dadswell and Eckersley 1938, Dadswell and Ellis
1939, Dadswell and Ingle 1948, Hess 1946, Heimsch
1942, Kribs 1930, Record 1939, 1941, Webber 1936,
1941) indicate that, on the basis of wood anatomy,
a close interrelationship exists among the members of
these six families. Plant taxonomists, using morphological
characteristics, have also come to the same
conclusion. However, arrangement of these families
into orders, based in large part upon such morphological
characteristics, has been inconsistent.
Earlier systems of classification, notably those of
Linnaeus (1753), de Candolle (1824-1873), and
Bentham and Hooker (1862-1883), were not based
on concepts of genetic relatedness as we know them
today. As such, the arrangement of the six families
within these systems is of little interest, other than
historical. It is not surprising, however, that these
families were closely grouped by de Candolle and
Previous numbers in this series appeared in Tropical
Woods (Yale University, School of Forestry) under the
running title, “The Woods and Flora of the Florida Keys”:
“Introduction” by W. L. Stern and G. K. Brizicky, 107:36-
65, 1957; “Compositae” by S. Carlquist, 109: 1-37, 1958;
“Goodeniaceae” by W. L. Stern and G. K. Brizicky, 109:
38-44, 1958; “Passifloraceae” by W. L. Stern and G. K.
Brizicky, 109345-53, 1958; and “Wood Anatomy and
Phylogeny of Batidaceae” by J. McLaughlin, 110: 1-15,
1959. “Capparaceae” by W. L. Stern, G. K. Brizicky, and
F. N. Tamolang appeared in Contributions from the United
States National Herbarium, 34(2) : 25-43, 1963.
These studies were initiated through a National Science
Foundation grant to William L. Stern in 1955.
1
TABLE 1.-Wood specimens of the Florida Keys “Pinnatae” examined
Collector and Number Lacation and Herbarium Collection
Catalog Number Voucher b c a l i t y
Species
ANACARDIACEAE
Metopium t a x i f e m (L.) Kmg & Urban Stern & Brizicky 566
Toxicodendro- radicans (L. ) Kuntze
BLTRSEPACEAI
Bursera simaruba (L.) Sarg. --
!GLIACW
Swietenia mahagani Jacq.
RUTACEAE
Amyris elernifera L
c i t r u s a u r a n t i i f o l i a (L. ) Swing1e
Zsnthaxylum f- (L.) Sarg.
Z. flavum Whl - -
SAPINDACEAE
3ar3~0spem:m hslicacabm I,.
Cupania glabra Sw.
-- Dodonaea viscosa (L.) Jacq.
Fxothea paniculata (Ass. ) Radlk.
Hypelate i r i f o l i a t a Sw
Sapindus sapanaria L.
SIMeR0UBACEp.E
Simarouba glaucB DC.
Suriana maritinla L. ~-
Stern 2643b
Stern 2633
Stern & B r i z i d q 171
Stern 1466
Stern 2624
Sterr. 2616
Sterr. & Brizicw 477
Stern 1455
Stern 2614
Stern & b i z i c k y 486
Stern 2653
Stern & Brizicky 514
stern zGn5
sterr., 2eam33, PhiE’S,
Rock, & Sweitzer 2761,
Stern 2656
Stern a: Bzizizky 419
Stern 1506
stern 2691
stern 128
Stern & Brizicky 298
Stern 1513
stern, Beaman, Fhipps,
Rock, & Sweitzer 2735
Stern & Brizicky 466
Stern 1467
stern 2612
Stern a: Brizicky 526
stern 1468
stem 2681
Stern & Brizicky 552
Stern 2659
Stem Brizicky 462
Stem 1497
Stern 2613
Stern & Brizicky 230
stern 1481
stern 2666
Y
MARY
WRY
Y
us
None
. W Y
Y
us
I W Y
Y
hWRY
Y
IrkRY
MARY
MARY
Y
35
MARY
Y
Y
US
MARY
Y
us
WRY
Y
US
. W Y
Y
VARY
Y
US
m
Y
US
MARY
Key Largo
Key Largo
Key Largo
Big Pim Key
Windley’s Key
Key Largo
Key Largo
Key largo
Key Largo
Key Largo
Key Largo
&ey Largo
Key Largo
Key I a x o
3ahia Honda Key
Key largo
3ig Pir.e Key
3ig Pke Key
Big Pine Key
sig Pine Key
Big Pine Key
Big Pine Key
Big Fire Key
Key largo
Windley’s Key
Key Largo
Windley’s Key
Windley’s Key
Windley’s Key
Key largo
Key largo
Key Largo
S i R Pine Key
Key Largo
Big Pine Key
Grassy Key
Big Pim Key
‘Method of c i t a t i o n of wood specimens fallows that recam.e?.ded by Stern 8nd Chanbers (l%C).
h o d epecimecs, f o r which no catalog number i s stated, refer t o fluid-presemed collectiors 9t the
University of Maryland.
NUMBER 5 3
Bentham and Hooker, for the similarity of gross
morphology is striking.
Engler (Engler and Diels 1936) divided these
families into two orders : Geraniales and Sapindales.
The Rutaceae, Meliaceae, Burseraceae, and Simaroubaceae
were placed in the Geraniales; the Anacardiaceae
and Sapindaceae were placed in the Sapindales.
Assignment of a family to an order was based
primarily on the orientation of ovule attachment :
family members with epitropous ovules were placed
in the Geraniales, while those with apotropous ovules
were placed in the Sapindales. The most recent revision
of Engler’s “Syllabus der Pflanzenfamilien”
(Melchior 1961) redistributes the members of the
Geraniales into a revised Geraniales and a newly
erected Rutales on the basis of histological differentiation
and a trend toward zygomorphy in the flowers.
The new Geraniales and Rutales are still segregated
from the Sapindales on the basis of ovule attachment.
The families concerned with in this study
which were included in the Geraniales are now
placed in the Rutales.
The phylogenetic schemes used by Hutchinson,
Hallier, and others, de-emphasized the ovular orientation
of Engler. Hutchinson (1926) erected three
orders to account for these families, separating them
largely on the presence or absence of gland-dotted
(pellucid dots) leaves (Figure 5). Those families
often having members with gland-dotted leaves were
placed in his Rutales (containing the Rutaceae, Simaroubaceae,
and Burseraceae) , while those families
without gland-dotted leaves were placed either in
the Meliales or Sapindales. The Meliales (containing
the Meliaceae) is characterized by members having
a stamina1 tube which is lacking in members of the
Sapindales (containing the Anacardiaceae and Sapindaceae)
. All of these orders are within Hutchinson’s
arborescent line of evolution. These three orders plus
the order Juglandales were grouped by Hutchinson
in the subphylum “Pinnatae.” The Juglandales was
later dropped from this subphylum (Hutchinson
1959). Hallier’s earlier treatment (1905) placed all
six families in his large cohort, Rosales, with the
note that it would be further subdivided after “. . .
more exhaustive examination.” Hallier ( 1912) later
combined the members of the Anacardiaceae and
Burseraceae into a single family, the Terebinthaceae,
which he included in his Rutales, along with Rutaceae,
Meliaceae, and Simaroubaceae. The Sapindaceae
was placed in his Sapindales. Wettstein (1935)
included all six families in his Terebinthales.
A survey of recently proposed phylogenetic systems
of classification reveals that the treatment of these
families is still not uniform. Cronquist (1968) assigns
the six “mutually interrelated” families to his Sapindales,
citing Heimsch’s work (1942) as a primary
reason. Takhtajan (1966) places the Sapindaceae in
his Sapindales, moving the remainder of the families
into his Rutales. Both orders are placed in the superorder
Rutinae (which also includes his Geraniales
and Polygalales). Thorne (1968) places all the families
in his Rutales, grouping the families into suborders
Rutineae (corresponding to Takhtajan’s Rutales)
and Sapindineae (containing the Sapindaceae).
(Table 2 offers a summary of the taxonomic
treatment of these six families.)
Suriana maritima Linnaeus, generally considered
within the Simaroubaceae, is seen by Gutzwiller
(1961), Jadin (1901), Record and Hess (1943),
Small (1911), Thorne (1968), Wilson (1911), and
others, as constituting a distinct monotypic family,
the Surianaceae. Cronquist ( 1968) accepts Gutzwiller’s
exclusion of Suriana from the Simaroubaceae,
but chooses to place this genus with Stylobasium in
his (Cronquist’s) Stylobasiaceae. This family is included
in Cronquist’s Sapindales. On the basis of
wood anatomy, Webber (1936) states that such a
separation of Suriana from the Simaroubaceae is not
justified.
The distribution and habit of each species dealt
with in this study vary widely and are listed separately.
Data concerning number of species, distribution,
and habit were obtained primarily from Brizicky
(1962a, 1962b, 1962c, 1963). The species are listed
by family. The collection site of each specimen is
indicated in Table 1.
ANACARDIACEAE. Metopium is a genus of three
species, occurring in the West Indies, southern Florida
and the Florida Keys, British Honduras, Guatemala,
and southern Mexico. Metopium toxiferum (L.)
Krug and Urban, a West Indian species, is found in
the hammocks, pinelands, and coastal dunes in southern
Florida and the Florida Keys. It occurs as a large
tree in the hammocks and as a shrub in the pinelands
throughout the Florida Keys.
Toxicodendron is a largely north temperate zone
genus of approximately 15 species of North American
and eastern Asiatic distribution. Toxicodendron ra4
SMITHSONIAN CONTRIBUTIONS TO BOTANY
TABLE 2.--Com~arison of taxonomic treatments
Order Sapindales
Stylabasiaceae'
Sapindaceae
Furseraceae
Anacardisceae
Simaroubaceae
Rutaceae
Meliaceae
h g l e r (Melchior 19647
lrder Rutalesb
Suborder Rutineae
Rutaceae
Simaroubaceae
Eurseracese
Meliaceae
kder Sapindales
Suborder Anacardineae
hacardiaceae
Suborder Sapindineae
Sapindsceae
Hutchinson (1959)
,ubphylw,. HcnataeC
Order. Rutales
Futaceae
Simaroubaceae
Bursereceae
Order Meliales
Meliaceae
Order Sapindales
Sapindaceae
Anacardiaceae
Tskhtajan (1966)
superorder Rutinae'
Order Rlteles
Anacaraiaceae
Burseraceae
Sinaroubaceae
Rutaceae
Meliaceae
Order %piridales
Sapindaceae
Thorne (1968)
luperarder. Rutiflarse
Order Futales
Suborder. Rutineae
Rutaceae
SLmaroubaceae
surianaceae
Meliaceae
3;rseraceae
hacardiaceae
Suborder. Sapindineae
Sapindaceae
aInc1uaes -
t h i s most recent revision of Engler's system (Melchior l % k ) the older Geraniales has been subdivided
into a revised Ceraniales and B newly erected Rutales (containing those families l i s t e d above i n addition to
others 1.
'This subphylum previously included the order Juglandales (1926 ).
'ffeviously the silperorder Einnatae .
dicans (L.) Kuntze (Figure 1) is widely distributed
in woods, thickets, fencerows, and swamps throughout
most of southern Canada, the United States,
northern Mexico, and the West I n d k 2 It occurs
as a woody vine throughout its range.
BURSERACEAE. Bursera is a genus of approximately
100 species, distributed throughout tropical
and subtropical America. Bursera simaruba (L.)
Sargent (Figures 2, 3) is found in southern Florida
and the Florida Keys, the West Indies, southern
Mexico, Central America, and northern South America.
It occurs as a large tree, primarily in the hammock
forests throughout the Florida Keys.
Swietenia, a genus of at least three
species, occurs in southern Florida and the Florida
Keys, the West Indies, Mexico, Central America,
Colombia, Venezuela, and the upper Amazonian
region. Swietenia mahagoni Jacquin (Figure 4) is
found in the West Indies, southern Florida and the
Florida Keys. On the Florida Keys it occurs in the
hammock forests. It is a large tree throughout its
range.
Amyris is a genus of approximately
20 species, occurring in southern Florida (including
the Florida Keys) and Texas, the West Indies, Central
America, and northern South America. Amyris
MELIACEAE.
RUTACEAE.
Toxicodendron is recognized as distinct from Rhus,
primarily on the basis of Barkley's monograph (1937).
elemifera Linnaeus is primarily a West Indian species,
occurring also in southern peninsular Florida and the
Florida Keys. It ranges in habit from a shrub to a
small tree (up to 50 feet tall, with trunks up to a
foot in diameter), and occurs in the hammock
forests throughout the Keys.
Citrus is a highly polymorphic genus with an
uncertain number of species (16 minimum and
possibly 145 maximum, Brizicky 1962a), native to
southern and southeastern Asia and Malaysia. Several
species are widely cultivated and have escaped
to all warm regions of the world (Brizicky 1962a).
Five species are recorded as more or less naturalized
throughout southern Florida and the Florida Keys.
Citrus ourantiifolia (L.) Swingle, the lime (the
single species of Citrus collected), is a tree native
to the East Indian Archipelago. It occurs on the
Florida Keys along roadsides and in secondary woods
(hammock forests).
Zanthoxylum, a genus of some 215 species, is
mainly pantropical in distribution (Brizicky 1962a),
with several species extending into temperate North
America and eastern Asia.3 Both of the species en-
'According to Record and Hess (1943), the genus
Zanthoxylum comprises only 15 species, all of north-temperate
distribution, while the genus Fagara comprises approximately
200 pantropical species. Brizicky ( 1962a) considers
Fagara as a synonym for the older Zanthoxylum.
NUMBER 5 5
countered in this study are considered native to the
West Indies (Brizicky 1962a). Zanthoxylum fagara
(L.) Sargent occurs in central and southern Florida,
including the Florida Keys, southern Texas, the
West Indies, Mexico, Central America, and South
America. It occurs as an armed (spined) shrub oi
small tree throughout its range. Zanthoxylum flavum
Vahl occurs as an unarmed small tree on the lower
Florida Keys (specifically Bahia Honda Key State
Park) and the West Indies. Both species occur in
hammock forests.
SAPINDACEAE. Cardiospermum, a genus of approximately
12 species, is primarily of tropical
American distribution, with one species occurring in
tropical West Africa and one ill-defined species
(Cardiospermum halicacabum L.4) of pantropical
distribution. Cardiospermum halicacabum (Figure 8 ) ,
a woody perennial vine, occurs in the hammock
forests on the Florida Keys.
Cupania is a tropical American genus of approximately
45 species and extends from Argentina and
Peru north to Mexico and into southern Florida, the
Florida Keys, and the West Indies. Cupania glabra
Swartz (Figure 9) occurs in the West Indies, the
Florida Keys, Mexico, and Central America as far
south as Costa Rica. It is a small tree of the hammock
forests, occurring in Watson’s Hammock on
Big Pine Key.
Dodonaea is primarily an Australian genus of approximately
60 species. One species occurs in Madagascar,
three occur in Hawaii, and one [Dodonaea
viscosa (L.) Jacquin] is reported as pantropical in
distribution. Dodonaea viscosa5 occurs as a small tree
‘ The treatment of the species Cardiospermum halicacabum
accepted in this study is as follows: C. halicacabum
comprises at least three varieties-halicacaburn, microcarpum
(syn. C. microcarpum H.B.K.), and corindum (syn. C.
corindum L.; C. keyense Small)-each of which is considered
by some authors (Brizicky 1963) as constituting a
separate pantropical species. All three varieties are reported
as occurring on the Florida Keys.
‘Brizicky (1963) refers to the pantropical species as
Dodonaea viscosa (L.) Jacquin, noting that this species includes
D. jamaicensis de Candolle and D. microcarya Small,
tentatively accepting SherfT’s concept of a single species
(D. viscosa) having three distinct pantropical varieties.
Sherff asserts that all of these varieties occur in Florida.
Brizicky states, however, that inadequate data make “. . . impossible
any conclusion regarding the nature and delimitation
of infraspecific categories of D. uiFcosa.” Therefore,
throughout this paper, the Florida Keys Dodonaea is referred
to as D. viscosa.
in the hammock forests and adjacent pinelands of the
Florida Keys.
Exothea is a tropical American genus of three species,
ranging from the West Indies, southern Florida,
Mexico and Central America, south to Costa Rica.
Exothea paniculata (Jussieu) Radlkofer occurs as a
small tree in the hammock forests and on calcareous
soils and shell mounds in southern peninsular Florida,
the Florida Keys, the West Indies, and Guatemala.
Hypelate, a genus comprising a single species, H.
trifoliata Swartz, occurs as a shrub or small tree in
the hammock forests (and rarely the pinelands of
Big Pine Key) of the Florida Keys and the West
Indies.
Sapindus is largely a tropical genus of approximately
13 species, three of which are distributed in
the Americas, with the remainder found in eastern
and southeastern Asia, Oceania exclusive of Australia,
and Hawaii. At least two of these species are
extratropical. The primarily tropical American species,
S. saponaria Linnaeus (Figures 6, 7), occurs as
a tree from Argentina, north into Mexico, the West
Indies, southern Florida, and the Florida Keys. It
is a member of the hammock forest flora on the
Florida Keys.
Simarouba is a widely distributed
tropical American genus comprising from six
to nine species. Sirnarouba glauca DeCandolle (Figure
10) occurs as a tree in southern Florida and the
Florida Keys, the West Indies, southern Mexico,
Central America, and part of South America. It is
an inhabitant of the hammock forests on the Florida
Keys.
Suriana is a monotypic genus of pantropical distribution.
The single species, S. maritima L. (Figure
11) is a small to large shrub (occasionally a small
tree) of the strand vegetation, occurring along seacoasts
throughout its range.
SIMAROUBACEAE.
Materials and Methods
Specimens studied in this investigation are listed in
Table 1. Dried wood specimens were obtained from
Dr. William L. Stern. Specimens bearing catalog
numbers of the Record Memorial Collection, Yale
University School of Forestry (YW)~, and the Na-
‘ The Samuel James Record Memorial Collection, originally
housed at the Yale University School of Forestry, was
transferred to the U.S. Forest Products Laboratory in Mad6
SMITHSONIAN CONTRIBUTIONS TO BOTANY
tional Collection of Woods, Smithsonian Institution
(USw) , were available as prepared slides. In addition,
fluid-preserved specimens bearing Stern collection
numbers 2612 through 2764 were utilized (see
Table 1). All wood samples were collected from
mature stems and are documented with herbarium
vouchers, with the exception of Bursera sirnaruba
Sargent, Stern 2624.
Microscope slides of specimens bearing Yale or
Smithsonian catalog numbers had been previously
prepared from unembedded, dried wood samples.
The fluid-preserved specimens were embedded in
celloidin prior to sectioning. All slides prepared specifically
for this study from fluid-preserved material
collected by Stern were sectioned on a sliding microtome.
All transverse sections were cut at 20p, while
radial and tangential sections were cut at 15p, 20p,
and 30p to provide different thicknesses for optimum
study of all cells and tissues. The sections were
stained in safranin and Heidenhain’s iron-alum
haematoxylin, dehydrated and cleared following
standard microtechnical procedures, and mounted in
Canada balsam. Exceptionally hard woods were softened
prior to sectioning, either in hydrofluoric acid,
as outlined in Sass (1958), or by boiling in Aerosol
OT solution in a reflux apparatus (a modification of
the procedure outlined by Ayensu 1967).
Macerations were prepared following a variation of
Jeffrey’s method. The original method, outlined in
Johansen ( 1940), was modified in the following manner:
tertiary butyl alcohol was used as the dehydrant
and, upon complete dehydration, a small amount of
stained cellular material was taken directly from the
tertiary butyl alcohol and placed into a watch crystal
containing a mixture of xylene and Canada balsam
of mounting consistency. The mass of cellular material
was then spread throughout the mounting medium
by gently mixing with a glass rod. A few drops
of this mixture were then placed on a microscope
slide and a cover slip added.
Selection of the diagnostic characters to be included
in the descriptions of each species was made from
those suggested by Tippo (1941). Measurements of
the length of both fibrous elements and vessel eleison,
Wisconsin, in December 1969. It is distinguished from
other wood collections in the Laboratory through the abbreviation
SJRw. Original wood collections at the Laboratory
bear the abbreviation MADw ; the Record Collection formerly
carried the abbreviation Yw.
ments were made from macerated material. Measurements
of pore distribution, pore diameter, and end
wall angle were made from sectioned material. All
measurements are recorded in microns (p) .
Fibrous elements were measured using a Bausch
and Lomb Tri-Simplex microprojector, except in a
few cases where, because of cellular breakage, accurate
measurement required the higher magnification
and resolution available only through the use of a
compound microscope. Vessel element lengths were
measured with both the microprojector and the
microscope, the latter was used when the small size
of the vessel elements prohibited accurate measurement
on the projector. The total length (tail to tail)
of vessel elements was measured, following the suggestions
of Chalk and Chattaway (1934, 1935).
Tangential pore diameters were measured from
outside wall to outside wall. Only solitary pores were
measured except in species where, because of the low
percentage of solitary pores, measurement of the tangential
diameters of pores arranged in radial multiples
was required. Pore distribution was determined from
transverse sections, while vessel element end wall inclination
was measured on tangential sections.
In measuring the lengths of the fibrous elements
and vessel elements, pore diameter, and inclination
of vessel element end walls, a total of 50 random
measurements of each character was made for each
species. From these measurements, a range, a most
frequent range (within which at least 50 percent
of the measurements made occur; hereafter abbreviated
MFR) , and a mean (average) were calculated,
except for the inclination of end walls, where only
a mean was calculated.
Pore distribution was determined by recording the
total number of solitary pores, radial multiples, and
pore clusters seen in a given field of view. Ten fields
were observed, and the total number of pores in
each distribution type was converted to a percentage
of the total number for all categories. In members
of the Rutaceae, pore chains in addition to radial
multiples are observed. Because of intergrades between
chains and multiples, and the difficulty in distinguishing
between each type, the pores of either
type are reported only as radially oriented (Table
The terminology used in this investigation generally
follows that suggested by the Committee on Nomenclature,
International Association of Wood Anato-
3).
NUMBER 5
55-90
2C-75
83-105
too-163
7
2-7
1-5
1-3
3-8
TABLE 3.-Pore arrangement, diameter, and wall thickness
65-10c
45-85
50-7C
POFE DISTRIBUTION (percent)
4-8
2-12
2-7
SFZCIES
ANACARDIACEAE
Metopiwn toxiferum
Taxicodendran radicans
SWSERACE.45
Bursera sinaruba -__
MELLACEAE
Swietenia mahagoni
RLTTACEAI
Amyris elemifera
Citms auranriifolia
Zamhoxylum fasara
2. flwm
SAPIhQACEAE
- -
Cardiospermum halicacaburr.
83-125
75-95
60-90
60-85
45-73
85-110
Cupsnia glabra
Cadonaea viscasa
Exathea paniculata
Hypelate t r i f o l i a t a
Sapindus saponaria
--
SIMAROUBACEAE
Simarouba glauca
Suriana maritime. --
4-13
2-7
3-7
2-8
3-7
2-5
Solitary
67
80
70
68
53
70
55 42
75
35
43
50
59
78
40
41
m l t i p l e s Radially
Oriented Clusters
D
Av g
-
-
78
52
88
-36
53
78
63
58
3Zd
-02
78
72
71
58
99
-75
58 -
IETER
Range
40-110
15-110
45-110
65-220
30-55
30-110
30-100
40-85
20-50
60-145
30-105
50-100
50-95
3C-80
40-150
85-260
30-85
m 1 Rangeo
’Numbers in parentheses i n d i c a t e t h e range of the number of pores Pound in each category.
b a l l s between pores in .radial multiples and c l u s t e r s are t h e t h i c k e s t .
CPore distribution reported a8 “radially oriented” because Of d i f f i c u l t y i n differentiating between
radial multiples and chains. Gxly i n the case of Amyris elemifera are the majority of the radially
oriented pores in d i s t i n c t chains.
dSmall pores (see description).
mists, International Glossary of Terms Used in Wood
Anatomy (1957), hereafter referred to as the IAWA
Glossary. General terms used in describing relative
sizes of structures (e.g., intervascular pit sizes and
fibrous element, cell wall thickness) are those suggested
by Record and Chattaway (1939).
The terms “fibrous elements” and “imperforate
tracheary elements” are used here interchangeably
and refer to the prosenchymatous cell types commonly
referred to as “fibers.” No attempt was made to
designate such fibrous elements as either fiber-tra-
‘ In the parlance of “wood technology” and “forest
products,” “fibers” also include the tracheids of gymnosperms.
cheids or libriform wood fibers, because of the tenuous
nature of the pitting encountered in the species
studied.
In describing the simple pits commonly found in
the parenchymatous cell types encountered in the
woods under study, the term “fenestriform” is used.
This term, meaning “windowlike,” is used to describe
any enlarged, oval to rectangular pit. These enlarged
pits are considerably broader than the intervascular
pits in the species being described. The fenestriform
pits most frequently seen in this study are the enlarged
simple components of a half-bordered, vessel
to parenchyma pit-pair. In some species both components
of vessel to parenchyma pit-pairs are fenestri8
SMITHSONIAN CONTRIBUTIONS TO BOTANY
form in nature. Since the simple fenestriform pits are
generally larger than the bordered pit of a halfbordered
pit-pair, a single fenestriform pit will frequently
subtend two or more bordered pits, resulting
in unilaterally compound pitting.
Because of the ambiguity, awkwardness, and lack
of precision involved in employing only names to
categorize vascular rays (Kribs 1935), a description
of the ray tissue of each species is given. The terms
“homocellular” and “heterocellular” are used in the
literal sense. Rays comprising only a single cell type
(for example, a ray which consists only of procumbent
cells) are referred to as homocellular. A ray containing
two or more cell types, even though one type
may be of only rare occurrence, is referred to as
heterocellular. Since varying degrees of the heterocellular
type of ray occur in the woods studied, reference
to the predominant cell type or types is given
in each description.
In the following anatomical descriptions, characters
common to all the species studied are included
in an initial description. The descriptions of the individual
species which follow this are arranged according
to family. The arrangement of both families
and the genera within each family is alphabetical.
Table 3 contains numerical data concerning the pore
distribution, pore diameters, and vessel wall thickness
of each species. Table 4 is a summary of pertinent
anatomical data obtained from each species and is
included in order to facilitate comparison.
Anatomical Descriptions
of the Woods of “Pinnatae”
Where growth rings are present, the wood in all
specimens studied is diffuse-porous (Figure 16), with
the exception of Toxicodendron radicans, which is
questionably diffuse-porous (Figure 19) . All perforations
are simple (Figure 32), with the exception of
a single multiple perforation observed in Metopium
toxiferum.
Intervascular pitting is alternate in all species
(Figures 30, 31 ) . Scalariform-like intervascular pitting
produced by coalescence of adjacent pits and
unilaterally compound intervascular pitting (Figure
31) occur to some extent in each species. Fenestriform
pits occur in the axial parenchyma and ray
parenchyma of each species, while in Bursera simaruba,
Metopium toxiferum, and Toxicodendron
radicans both components of vessel to parenchyma
pit-pairs are commonly fenestriform (Figure 32).
Unilaterally compound vessel to parenchyma pitting
occurs in all species.
The fibrous elements of all species studied have
oval to slitlike simple or slightly bordered pits predominating
on their radial walls (Figures 28, 29).
The slitlike inner apertures of any given pit-pair may
be either crossed at angles to one another, or directly
superposed. Both configurations are frequently observed
on a single specimen. Axial parenchyma is
present in all species. Vascular tracheids and disjunctive
paratracheal parenchyma cells are found in
all species.
ANACARDIACEAE
Metopium toxiferum (L.) Krug and Urban: Faint
growth rings are present. The pores are angular
to rounded, with vessel element walls varying in
thickness from 2p to 7p.
Vessel element length averages 375p, with a range
of 19Op to 670p and a MFR of 330p to 450p. Perforations
are simple, with the single exception of a
multiple perforation observed in maceration. The
arrangement of perforations in this instance is such
that neither the term reticulate nor foraminate is
accurately descriptive. It should be noted that because
of the fenestriform nature of vessel wall pits
involved in vessel to parenchyma .pitting, description
of this perforation plate as multiple may not be accurate.
The structure seen may actually be a collection
of such fenestriform vessel wall pits, arranged
at the end of the vessel element in such a manner that
the impression of a multiple perforation is given.
Vessel element end walls are inclined at an average
of 44’. In general, the vessels are ligulate.
Intervascular pitting comprises medium-sized pits
ranging from 7p to lop in diameter. Pit borders are
round to somewhat angular; pit apertures are oval
and included within the borders.
Both vessel to axial parenchyma pitting and vessel
to ray parenchyma pitting are fenestriform in nature,
both members of a vessel to parenchyma pit-pair are
oval to somewhat angular and simple.
The imperforate tracheary elements are nonseptate.
Fibrous elements are gelatinous in nature (Figure 34),
and, as such, two measurements of wall thickness
were made. The rigid lignified portion of the secNUMBER
5 9
ondary wall is from l p to 3p thick while the combination
of rigid and nonrigid secondary walls seldom
exceeds 6p. As such, the wall thickness (combined)
ranges from thin to very thick. The average length
of the fibrous elements is 683p, with a range of 330p
to 970p and a MFR of 560p to 860p.
Vascular rays are predominantly bi- and triseriate.
Some uniseriates are present and a few rays up to
five cells wide are seen. These may contain horizontal
intercellular canals. All rays are heterocellular, comprising
upright, square, and procumbent cell types.
The bi- and triseriate rays frequently possess uniseriate
wings of from 2 to 4 rows of square and upright
cells, or both, the remainder of the ray comprising
procumbent cells. Many of the uniseriate rays appear
to be composed largely of square and upright cells,
or both. The uniseriate rays range from 1 to 8 or
more cells in height, while the bi- and triseriate rays
are up to 20 cells (400p) or more in height. Starch
occurs in many of the ray cells.
The horizontal intercellular canals seen in the rays
of this species are of infrequent occurrence in Stern
2643, but rather frequent in Stern @ Brizicky 556.
The canals are surrounded by an epithelial lining (1
to 2 cells thick) composed of small, square to angular
cells with thin isotropic (optically inactive) cell
walls. The cells external to the epithelial lining are
of similar shape and size, but with somewhat thicker,
optically anisotropic cell walls. These cells tend to
intergrade with the larger, typical procumbent cells.
The canals seen in Stern 2643 are apparently at an
early stage of development, possessing small intercellular
spaces or canals, while those seen in Stern
@ Brizicky 556 are of a later stage of development,
having massive intercellular spaces or canals. Many
of these older canals lack any organized epithelial
layer (apparently due to lysigeny). In the latter
specimen, the canals are often nearly as wide as the
ray in which they occur. In both specimens a dense,
rather darkly staining substance is found in many of
the canals, in addition to remnants of epithelial cell
walls. It is apparent that these canals are secretory
in nature.
Axial parenchyma is present in both apotracheal
and paratracheal arrangements. Apotracheal parenchyma
forms irregularly spaced bands which vary in
width from 1 or 2 cells to 10 or more cells wide.
Bands are independent of growth rings. Paratracheal
parenchyma is aliform to confluent, leading to some
localized banding. All the axial parenchyma cell
types frequently contain starch grains. Crystalliferous
strands are absent.
Thin-walled tyloses are seen extending into the
vessels from both axial and ray parenchyma (Figure
34). In longitudinal section, a high percentage of the
fenestriform vessel to ray pits are sites of tylosis formation.
Toxicodendron radicans (L.) Kuntze : The wood
is diffuse-porous (Figure 19), although the outer
growth rings tend to be ring-porous ; faint growth rings
are present. The pores are circular to somewhat
angular, with walls ranging in thickness from lp to
5p. Tangential pore diameters range from 15p to
11Op. A study of macerated material, however, reveals
a number of smaller vessel elements, having
diameters of less than 15p (as measured on macerated
material). These vessels could not be included in the
measurements of diameters in transverse section, because
they are not readily distinguishable from imperforate
tracheary elements.
Vessel element length averages 250p, with a range
of 120p to 360p and a MFR of l60p to 300p. Vessel
element end walls are inclined at an average of 41°.
The vessel elements are generally ligulate.
Intervascular pitting comprises small bordered pits
ranging in size from 4p to 6p in diameter. The pits,
generally restricted to the ends of the vessel elements
(pitting on the body of the vessel elements is relatively
infrequent, because of the high percentage of
solitary pores) , possess circular to lenticular apertures
included within rounded to angular borders.
Vessel to axial parenchyma pitting comprises halfbordered
to simple pit-pairs. The component pits
of a simple pit-pair, in the vessel element wall and
the axial parenchyma wall, are both fenestriform in
nature. Half-bordered pit-pairs are rather infrequent,
the bordered pit of the vessel element wall generally
having large lenticular apertures extending to lenticular
borders. These bordered pits are generally larger
than the intervascular bordered pits and intergrade
with the fenestriform simple vessel element pits. Vessel
to ray parenchyma pitting is very infrequent.
When present, it resembles the vessel to axial parenchyma
pitting.
The imperforate tracheary elements are septate,
each cell having a single septum. Fiber walls vary
in thickness from 1p to 5p and range from very thin
to thick. A study of macerated material reveals that
10 SMITHSONIAN CONTRIBUTIONS TO BOTANY
the fibrous elements may have either attenuated or
truncate end walls. Fibrous elements contain massive
amounts of starch. The average length of the
fibrous elements is 374p, with a range of 230p to 560p
and a MFR of 300p to 440p.
Vascular rays are uniseriate and biseriate, although
in some cases, a portion of a biseriate ray may be up
to three cells wide. Square and upright cell types
occur most frequently, while the procumbent cell
type is rare. The cell type found in any given horizontal
row is frequently constant, with one row composed
entirely of upright cells while another is composed
of square cells. The occurrence of two cell types
within the same horizontal row is relatively infrequent.
Arrangement of cell types does not follow a
pattern. The uniseriate rays vary in height from 2
cells to 30 cells or more. Approximately 50 percent
of the ray cells contain a dark-staining substance of
unknown composition. Ray cells generally contain
large amounts of starch.
Axial parenchyma is present in both apotracheal
and paratracheal arrangement. Diffuse parenchyma
apparently comprises noncrystalliferous strands. Since
the fibrous elements of this species are living (septate
and store starch), it was difficult to determine whether
cells, seen in either transverse or longitudinal section,
were axial parenchyma cells or fibers. Since
the other parenchymatous cells (paratracheal parenchyma
and ray parenchyma) frequently contained a
dark-staining substance, this character was used as
the distinguishing criterion ; cells containing the darkstained
substance, when viewed in transverse section,
were interpreted as diffuse parenchyma. The paratracheal
parenchyma is scanty vasicentric to vasicentric,
and, as mentioned previously, frequently contains
a dark-staining substance similar to that seen
in the ray tissue.
A large number of small, thin-walled tyloses are
present in many of the vessel elements. The tyloses
contain the dark-staining substance seen in the paratracheal
parenchyma cells. This is to be expected,
since tyloses are extensions of parenchyma cells into
the vessel lumen.
BURSERACEAE
Bursera simaruba (L.) Sargent: Growth rings are
absent. The pores are somewhat angular and have
walls lp to 3p thick.
Vessel element length averages 531p and ranges
from 300p to 770p; the MFR is 495p to 700p. Vessel
element end walls are inclined at an average of
48'. The vessels may be either ligulate or eligulate.
Intervascular pitting comprises medium-sized pits
ranging from 7p to lop in diameter. The pit apertures
are lenticular and included within polygonal
pit borders.
Vessel to axial parenchyma pitting is rare because
of the scarcity of paratracheal parenchyma. Where
it occurs, it is sporadic and irregular to alternate
and larger than the intervascular pitting. Vessel to
ray pitting differs from the above in that it is variable
in form, ranging from large, generally rectangular
fenestriform pits to small, oval pits (Figure 3 2 ) .
Both components of the former type of vessel to ray
parenchyma pit-pair are fenestriform in nature. Both
vessel to axial parenchyma pitting and vessel to ray
parenchyma pitting are half-bordered.
The imperforate tracheary elements are septate,
having from 3 to 8 septa per cell, 3 being the most
common. Fibrous elements in Stern 2624 contain
massive amounts of starch (Figures 12, 13) ; starch
grains are also seen in Stern 1466. Wall thickness of
fibrous elements may be classified as very thin, 2p to
4p thick. The average length of the fibrous elements
is 809p, the range 440p to 116Op and the MFR 730p
to 950p.
Vascular rays are predominantly multiseriate ; some
uniseriate and biseriate rays are seen. All rays are
heterocellular, although some of the uniseriate rays
appear to be homocellular when seen in tangential
section. A survey of 10 radial sections, however, did
not reveal such homocellular rays. This is apparently
related to the nature of cell arrangement. In radial
section, there are no horizontal rows consisting of
only one type of ray cell. Those rows containing
procumbent cells also contain square and upright
cells, or both. Tangential sections of the same ray
taken at different points would appear to be homocellular
at one point and heterocellular at the other. The
height of the uniseriate rays is up to 350p (20 cells).
These are far less frequent in occurrence than are
the multiseriate rays.
Multiseriate rays are up to 500p (30 cells) in height
and up to loop in width. The body of the multiseriate
ray is composed of procumbent cells. These rays
generally have uniseriate wings, 1 to 3 cells high,
composed of upright and square cells, or both. The
NUMBER 5 11
rows of procumbent ray cells are uniform, as is generally
true of the rows of upright and square cells
of the vertical wings. The upright and square ray
cells of this ray tissue frequently contain optically
anisotropic, prismatic crystals and starch grains.
Horizontal intercellular canals are seen in many
of the multiseriate rays (Figure 24). These canals
are circular in cross section (as seen in tangential
section) and surrounded (lined) with thin-walled
epithelial cells. The walls of the epithelial cells are
optically isotropic (optkally inactive when viewed
under crossed nicols) .
The arrangement of axial parenchyma is difficult
to determine, because of the difficulty in distinguishing
between axial parenchyma cells and the thinwalled,
septate, living fibrous elements. As mentioned
previously, the fibrous elements store starch and, as
such, carry on one of the functions of axial parenchyma.
Determination of the presence of axial parenchyma
was made only through study of macerations.
Distinction between fibrous elements and axial parenchyma
cells in macerated material was based on the
pitting and on the cell wall configuration: the transverse,
truncate, horizontal end walls of the parenchyma
cells and the septa of the attenuated fibers.
The axial parenchyma seen in macerations may be
classified as scanty vasicentric. Apotracheal parenchyma
may also be present but is not distinguishable
in transverse section.
MELIACEAE
Swietenia mahagoni Jacquin : Growth rings are
present. Pores are rounded to somewhat angular with
vessel element walls varying in thickness from 3p
to 8p.
Vessel element length averages 437p, with a range
of 200p to 720p and a MFR of 390p to 515p.. Vessel
efement end walls are inclined at an average of
62'. Vessel elements may be either ligulate or eligulate.
Intervascular pitting comprises minute bordered
pits ranging in size from 2p to 3p in diameter. Pit
borders are rounded to angular; pit apertures are
lenticular to oval and are included within the borders.
Vessel to axial parenchyma pitting and vessel to
ray parenchyma pitting are very similar in size,
shape, and arrangement. Both types of vessel to
parenchyma pitting are half-bordered. The bordered
pits of the vessel wall are arranged in an
alternate pattern, these pits coinciding in shape and
size to intervascular pits. The simple pits of the
parenchyma walls are oval to elongate and often
fenestriform in nature.
Imperforate tracheary elements are septate, having
a wall thickness that varies from 2p to 7p, and ranges
from thin to thick. Septa are thin and there are
two per cell. The average length of the fibrous elements
is 981p, with a range of 650p to 1250p and a
MFR of 880p to 1160p.
The vascular rays are uniseriate to multiseriate,
with rays infrequently up to five cells wide; 3- and
4-seriate rays are the most frequent. All rays are
heterocellular. The infrequent uniseriate rays are
short, ranging from a single cell to eight or more cells
in height, and composed almost entirely of square
and upright cells, or both. Biseriate rays are longer
than uniseriate rays, ranging from 5 to 15 or more
cells in height, and composed of the same cell types
seen in the multiseriate rays. Multiseriate rays range
in height from 10 cells (250p) to 30 cells (700p)
or more, the longer rays generally resulting from
vertical fusion of two rays. Bi- and multiseriate rays
comprise procumbent, square, and upright cell types.
The procumbent cell type generally makes up the
multiseriate portion of a given ray, while the square
and upright cell types comprise the one- to manycelled
uniseriate wings or margins (Figure 22). Many
ray cells contain an opaque, dark-staining substance
of unknown composition. Most ray cells contain
starch. Marginal cells are frequently crystalliferous
idioblasts. The ray tissue is storied.
Axial parenchyma occurs in both apotracheal and
paratracheal arrangement. Apotracheal parenchyma
is present mainly as marginal bands (initial). Some
diffuse parenchyma is also present. Both types of
apotracheal parenchyma cells contain starch; either
may be crystalliferous, the occurrence of crystalliferous
idioblasts is infrequent and random. Crystalliferous
strands are not present. The paratracheal
parenchyma is scanty vasicentric to vasicentric. Both
types of axial parenchyma cells frequently contain
the same dark-staining substance reported in the ray
cells.
Vessels generally contain this dark-staining opaque
substance also. The vessel elements tend to be storied
in addition to the rays.
12 SMITHSONIAN CONTRIBUTIONS TO BOTANY
RUTACEAE
Amyris elemifera Linnaeus: Growth rings are present,
but not distinct. Pores are rounded in cross section,
and have walls 4p to 8p thick. Chains are the
predominant, radially oriented, pore group.
Vessel element length average 250~, with a range
of 110p to 350p and a MFR of 220p to 330p. Vessel
element end walls are inclined at an average of
55’. The vessel elements are generally ligulate.
Intervascular pitting comprises minute bordered
pits ranging from 3p to 4p in diameter. Pit apertures
are slitlike to oval and included within the circular
pit borders. Vessel to axial parenchyma pitting is rare,
owing to the scarcity of paratracheal axial parenchyma;
where it occurs, it is alternate. Vessel to ray
parenchyma pitting is alternate. In both types of vessel
to parenchyma pitting, the pit-pairs are halfbordered;
the vessel pits are similar in size and shape
to the intervascular pits described above, and the
parenchyma pits are fenestriform and simple.
Imperforate tracheary elements are nonseptate,
having thick cell walls 3p to 7p in thickness. The
aveage length of these fibrous elements is 443p, with
a range of 270,~ to 660p and a MFR of 375p to 5301.
Vascular rays are uniseriate and homocellular, all
cells are procumbent. Although the orientation of
individual ray parenchyma cells is horizontal in all
cases, cell length varies, and in some instances, some
cells in a horizontal row are nearly square. However,
since these “square” cells are not a consistent character,
either in their occurrence or their arrangement,
I feel the designation of “homocellular” is justified.
Rays average from 3 to 10 cells in height, rarely up
to 19 cells (200p) high.
Axial parenchyma is present as diffuse and banded
apotracheal parenchyma and as scanty paratracheal
parenchyma. The banded apotracheal parenchyma is
1 to 3 cells wide and continuous; the diffuse parenchyma
is present as crystalliferous strands comprising
2 to 8 cells (as viewed in tangential section). The
crystalliferous parenchyma cells (idioblasts) are
much enlarged. No starch grains were seen, because
of the acid-softening treatment.
Small thin-walled tyloses are present (Figure 33) .
An amorphous material is seen in some vessels, perhaps
because of gummosis of the parenchyma cells
forming the tyloses.
Citrus aurantiifolia (L.) Swingle: Growth rings
are present. The pores are circular, with walls ranging
from 4p. to 8p thick. Radial multiples are the
predominant, radially oriented, pore group.
Vessel element length averages 273p, with a range
of 150p to 420p and a MFR of 235p to 340p. Vessel
element end walls are inclined at an average of
58’. Vessel elements may be ligulate or eligulate.
Intervascular pitting consists of small pits, ranging
from 4p to 6.p in diameter. Pit apertures are rounded
to oval and included within round to polygonal borders.
Vessel to axial parenchyma pitting is alternate.
The pits found in the vessel element walls are similar
in size to intervascular pits, while those found in the
axial parenchyma walls are larger and simple. Vessel
to ray parenchyma pitting is alternate and resembles
the vessel to axial parenchyma pitting.
Fibrous elements are nonseptate, having thin walls
from 2p to 5.u thick. The average length of the
fibrous elements is 752p, with a range from 400p to
1150p and a MFR of 560p to 890p.
Vascular rays are uniseriate to triseriate, some rays
rarely 4 cells wide. The uniseriate rays range from 1
to 12 cells (150p) in height and are heterocellular.
The biseriate and triseriate rays are up to 40 cells
(500p) in height and are heterocellular, a few having
uniseriate wings of from 1 to 4 cells high. In
the case of both uniseriate and multiseriate rays, the
great majority of cells are procumbent. Very few
upright cells were seen in the material studied, arrangement
of the cell types follows no pattern, and
although the margins of the multiseriate rays may
be a mixture of procumbent and square cells, the
body of the ray comprises only procumbent cells. The
ray cells in contact with vessel elements are frequently
disjunctive. Most ray cells contain starch grains.
Axial parenchyma is present in both apotracheal
and paratracheal arrangements. The apotracheal
parenchyma is banded, diffuse, and diffuse-in-aggregates,
some of which comprise crystalliferous
strands of from 3 to 20 cells. The banded apotracheal
parenchyma is made up of axially elongate parenchyma
strand cells, some of which have further subdivided
and are crystalliferous (crystalliferous
strands). Many of the cells of the diffuse and diffuse-
in-aggregates parenchyma are crystalliferous.
The crystalliferous idioblasts are generally much enlarged,
containing optically anisotropic prismatic
NUMBER 5 13
crystals (Figure 25). The bands of axial parenchyma
are from 1 to 4 cells wide and are continuous. Paratracheal
parenchyma is scanty vasicentric and sometimes
aliform. Axial parenchyma cells are frequently
disjunctive. Most, if not all, of the axial parenchyma
cells contain starch.
The vessels often contain a granular to nongranular,
translucent amorphous material aggregated
on or near the perforation plates.
Zanthoxylum fagara (L.) Sargent : Faint growth
rings are present. Pores are circular, with walls ranging
in thickness from 2p to 12p. Radial multiples
are the predominant radially oriented pore group
(Figure 14).
Vessel element length averages 261p, with a range
of 145p to 465p and a MFR of 210p to 310p. Vessel
element end walls are inclined at an average of
64’. Vessel elements may be either ligulate or
eligulate.
Intervascular pitting comprises minute bordered
pits ranging from 2p to 3p in diameter. Pit apertures
are oval to lenticular and included within rounded
borders.
Vessel to axial parenchyma pitting and vessel to
ray parenchyma pitting are similar in size, shape,
and arrangement. The pit-pairs are half-bordered,
with the bordered vessel element pits similar in size,
shape, and arrangement to the intervascular bordered
pits described above. The simple parenchyma
pits (both axial and ray parenchyma) are generally
circular to oval and are either approximately the
same size as the bordered pits or large, elongate, and
fenestriform.
The imperforate tracheary elements are nonseptate,
having walls which range in thickness from 2p to 6p
and from thin to very thick (lumens entirely occluded).
The length of the fibrous elements averages
735p, with a range of 400p to 11 75p and a MFR of
600p to 1OOOp.
Vascular rays are predominantly uniseriate and
biseriate, with a few triseriate for at least a part of
their length. All ray types are heterocellular. Uniseriate
raps are frequently short, ranging in height from
2 to 6 cells or more, and are composed of either
square or upright cells, or both. A second type of
uniseriate ray is generally higher, ranging up to 10
cells or more in height, and consists of procumbent
cells in addition to square and upright celIs, or both.
The biseriate rays are generally higher than the
uniseriates, ranging up to 400p (30 cells) or more
in height, the biseriate portion of the ray is typically
composed of only procumbent cells, while the uniseriate
margins or “wings” are composed of 1 to 5 or
more horizontal rows of square and upright cells, or
both. Starch is not present in the ray cells, possibly
because of the hydrofluoric acid treatment of the
specimen (Stern 2625) prior to sectioning.
Axial parenchyma is present in apotracheal and
paratracheal arrangement. The apotracheal parenchyma
occurs as continuous bands, ranging from 2 to
7 or more cells in width, comprising strand parenchyma.
Generally there are two cells per strand, although
in some cases, one or both of these cells has
further subdivided several times, giving rise to short
strands of crystalliferous idioblasts. Scanty diffuse
parenchyma comprises the same cell type as described
above. The paratracheal parenchyma is scanty vasicentric.
Irregular and continuous periclinal cavities occur
throughout the xylem of Stern 2625 (Figures 26, 27).
These cavities are apparently traumatic in origin and
contain an evenly staining, homogeneous, opaque to
transparent substance. Many of the vessels contain
a granular to nongranular (similar in appearance to
the homogeneous material seen in the traumatic
cavities described above) , translucent to transparent
material.
Zanthoxylum flavum Vahl: Growth rings are
present. Pores are circular to somewhat angular, with
the vessel element walls ranging in thickness from 2p
to 7p. The bulk of the radially oriented pores are
intergrades between radial multiples and chains in
which at least some pores have flattened tangential
walls.
Vessel element length averages 575p, with a range
of 300p to 750p and a MFR of 475p to 650p. Vessel
element end walls are inclined at an average of
44’. The vessel elements are generally ligulate.
Intervascular pitting comprises small bordered pits
ranging in size from 4p to 6p in diameter. The pit
apertures are oval to lenticular and are included
within rounded to somewhat angular borders.
Vessel to axial parenchyma pitting and vessel to
ray parenchyma pitting is similar in size, shape, and
arrangement. The pit-pairs are half-bordered and
alternately arranged. The bordered pit of the vessel
element wall coincides in size and shape with those of
the intervascular pit-pairs. Simple pits of the paren14
SMITHSONIAN CONTRIBUTIONS TO BOTANY
chyma wall are round to oval and frequently elongate,
the latter fenestriform.
The imperforate tracheary elements are nonseptate.
having walls that vary in thickness from 2p to 5p
and range from thin in early wood to thick and very
thick in late wood. These walls are optically inactive
and, as such, may indicate that the fibers are actually
gelatinous. The average length of the fibrous elements
is 1125p, with a range of 735p to 1428~ and
a MFR of 945p to 1300p.
Vascular rays are uniseriate to triseriate, with
biseriate rays predominating. The uniseriate rays
range from 1 to 7 or more cells high and most
frequently comprise only square and upright cells,
or both. Some procumbent cells are seen in the
uniseriate rays. Bi- and triseriate rays are approximately
the same size, ranging from 5 cells to over
25 cells (600p) in height. In both the bi- and triseriate
rays, the multiseriate portion of the ray comprises
procumbent cells, while the uniseriate “wings”
or margins frequently comprise only square and upright
cells or both. The rays are heterocellular, comprising
all three cell types. Ray cells contain massive
amounts of starch and are frequently crystalliferous.
Axial parenchyma is present in apotracheal and
paratracheal arrangements. The apotracheal parenchyma
occurs as continuous bands, which are
usually, but not necessarily, marginal. When clearly
marginal, these bands are initial and are 1 to 2 cells
in width. The bands comprise strand parenchyma,
many of which, having further subdivided, contain
nonenlarged, optically active crystals. Diffusely arranged
crystalliferous strands are infrequently seen.
The paratracheal parenchyma is exceedingly scanty,
not common to every vessel, and never completely
vasicentric. All types of axial parenchyma contain
massive amounts of starch.
SAPINDACEAE
Cardiospermum halicacabum L. : Faint growth rings
are present. Pores are rounded to somewhat angular
with walls varying in thickness from 4p to lop thick.
Two distinct sizes of vessel elements are present in
this species (Figure 35.) The smaller of the two
sizes is generally angular and arranged in radial
multiples. These vessel elements are ligulate and
have end walls inclined at an average of 45’ (the
measurement of the end wall angles are made on
macerated material) . These small vessel elements
intergrade with vascular tracheids.
The larger of the two sizes are rounded and are
either solitary or arranged in clusters. The large
vessel elements are either ligulate or eligulate, with
nearly horizontal end walls.
The average end all inclination of the combined
vessel element types, as measured in tangential section,
is 76’. The average vessel element length is
200p, with a range of 130p to 290p and a MFR of
Intervascular pitting comprises small pits, ranging
in size from 4p to 6p in diameter. Pit apertures
are oval to lenticular. Pit borders are rounded.
Vessel to axial parenchyma pitting and vessel to
ray parenchyma pitting, when viewed in section, are
similar in appearance. The pit-pairs in both types
of pitting are half-bordered. Pits in the vessel element
wall are similar in size, shape, and arrangement
to intervascular pits. A study of macerations
reveals that the simple pits of the ray parenchyma
are frequently small and slitlike to oval, while those
of the axial parenchyma are large, oval to elongate,
and fenestriform.
Imperforate tracheary elements are frequently
septate, having walls from 2p to 4p thick, ranging
from very thin to thick. The average fibrous element
length is 533p, with a range of 350p to 800p and a
MFR of 440p to 60011..
A study of macerations indicates that two distinct
types of fibrous elements are present. One type is
typically thick-walled, having attenuated ends and
infrequent, thin, solitary septa. The second type of
fibrous element is generally thin-walled, having
truncate end walls. This second type is frequently
septate. Septa are thick and range from 1 to 3 or
more per cell. Pitting is similar in both types and
each may contain starch.
Vascular rays are uniseriate to multiseriate, some
rays are 4 or more cells wide. The multiseriate rays
frequently have uniseriate margins. The rays range
in height from a few cells to over 40 cells (800p).
The ray tissue is heterocellular, comprising upright,
square, and procumbent cell types. Upright and
square cells are most frequent, while procumbent
cells are relatively rare. The arrangement of cell
types follows no discernible pattern. Two or more
cell types are commonly found in any given horizontal
row. Ray cells are often crystalliferous or
160p to 250p.
NUMBER 5 15
contain starch. Some of the ray cells contain a darkstaining,
transparent to opaque substance of unknown
composition.
Axial parenchyma is present in both apotracheal
and paratracheal arrangement. Diffuse parenchyma
usually comprises crystalliferous strands. Additional
apotracheal parenchyma is present in the form of a
discontinuous band that may have been traumatic
in origin in my specimen. Cells in these apotracheal
parenchyma bands are also frequently crystalliferous.
The crystalliferous idioblasts are nonenlarged rectangular
cells, each containing a single optically
anisotropic prismatic crystal. They are arranged in
short vertical strands of from 3 to 10 or more cells.
The paratracheal parenchyma is generally scanty
vasicentric, although a few cases of vasicentric are
seen. Axial parenchyma cells are frequently disjunctive.
Both types of axial parenchyma contain massive
amounts of starch and may contain the dark-staining
substance seen in ray cells.
Cupania glabra Swartz: Growth rings are present
but not distinct. The pores are rounded, having walls
from 2p to 7p thick.
Average vessel element length is 414p, with a
range from 65p to 610p and a MFR from
340p to 500p. Vessel element end walls are inclined
at an average of 44'. The vessel elements are generally
ligulate.
Intervascular pitting comprises minute bordered
pits which range from 2p to 4p in diameter. Pit
borders are rounded; pit apertures are rounded to
elliptical and are included within the borders.
Vessel to axial parenchyma pitting is alternate to
scattered. Many of the pits in the parenchyma cell
walls are large, simple, and fenestriform with irregularly
shaped margins. The pits in the vessel walls
are slightly to completely bordered. Vessel to ray
parenchyma pitting is the same as that described for
vessel to axial parenchyma pitting.
The imperforate tracheary elements are septate.
Most of the fibrous elements contain 2 or more
septa. The cell walls are 2p to 5p thick and are thin
as compared with the diameter of the lumen. The
average length of the fibrous elements is 697p, with
a range of 375p to 950p and a MFR of 630p to
840p.
Vascular rays are, for all intents and purposes,
uniseriate. A few rays possess biseriate segments but
these are localized and never extend the length of a
ray. The rays may be up to 20 cells (300p) or more
in height, but generally range from 4 to 10 cells
high. Rays are heterocellular, comprising mainly
procumbent and square cells, with upright cells occurring
infrequently. There is no pattern of arrangement
of cell types, although the procumbent cell
type makes up the bulk of most rays, while the square
cell type frequently occurs in marginal rows. Both
square and procumbent cells occur in the same horizontal
row. Most of the ray cells contain a darkstaining,
transparent to opaque substance of unknown
composition.
Axial parenchyma is present in both apotracheal
and paratracheal arrangements. Apotracheal parenchyma
is mainly diffusely arranged, crystalliferous
strand parenchyma. There is continuously banded
apotracheal parenchyma 1 to 3 cells wide. The
diffuse crystalliferous strands are of frequent
occurrence, and range up to 30 cells or more
in height. Strand cells, when viewed in longitudinal
section, are rectangular, with most of the cells in a
given strand being crystalliferous. Apotracheal bands
comprise primarily crystalliferous strand parenchyma,
but unlike the diffuse strands, the cells of the bands
contain the same dark-staining substance seen in the
ray cells. The paratracheal parenchyma is scanty
vasicentric and frequently contains the same darkstaining
substance previously mentioned,
Dodonaea viscosa (L.) Jacquin: Growth rings are
absent. Pores are circular with walls varying in
thickness from 3p to 7p.
Vessel element length averages 234p, with a range
of 120p to 330p and a MFR of 200p to 270p. Vessel
element end walls are inclined at an average of 54'.
Vessel elements are either ligulate or eligulate.
Intervascular pitting comprises minute bordered
pits ranging from 2p to 4p in diameter. Pit borders
are rounded; pit apertures are lenticular and slightly
extended beyond or included within the borders.
Vessel to axial parenchyma pitting and vessel to
ray parenchyma pitting are very similar and both
fit the following description. The arrangement of
pits in the vessel wall is alternate. Vessel to parenchyma
(both types) pit-pairs are half-bordered; the
bordered pit of the vessel wall coincides in size and
shape to the intervascular pits, while the simple pits
of the parenchyma wall are generally irregularly
shaped, ranging from circular to elongate, and are
frequently fenestriform.
16 SMITHSONIAN CONTRIBUTIONS TO BOTANY
Imperforate tracheary elements are nonseptate,
having a wall thickness from 3p to 7p which ranges
from thick to very thick, the lumens of some cells
entirely occluded. The average length of the fibrous
elements is 525p, with a range of 250p to 720,~ and a
MFR of 440p to 650p.
Vascular rays are predominantly uniseriate. Some
biseriates are present, either as short biseriate segments
in otherwise uniseriate rays or as completely
biseriate rays. The rays are heterocellular, comprising
procumbent and square cells. Very few upright cells
are seen. There is no discernible pattern of cell arrangement
and both square and procumbent cell
types frequently occur in the same horizontal row.
There is a tendency, however, for the main body of
a given ray to be composed primarily of procumbent
cells. The occurrence of the square cells is sporadic
in all cases, their arrangement random.
Uniseriate rays range in height from 2 to 20 cells
(300p) or more, while the biseriates generally range
from 5 to 15 cells in height. The ray cells frequently
contain a dark-staining, transparent to opaque substance
of unknown composition.
Axial parenchyma is present in both apotracheal
and paratracheal arrangement. Apotracheal parenchyma
is primarily diffuse, consisting mainly of
crystalliferous strands. Some continuously banded
parenchyma occurs, these bands ranging in width
from 1 to 3 or more cells. The diffuse crystalliferous
strands are generally short, usually 10 or fewer cells
per strand, and composed of slightly enlarged idioblasts,
each containing a single optically anisotropic
prismatic crystal. The paratracheal parenchyma
ranges from scanty vasicentric to aliform, with infrequent
confluent banding occurring. This banding
is local (not continuous) and is definitely associated
with the vessel elements. Axial parenchyma frequently
contains the dark-staining material seen in
the ray cells.
Exothea paniculata (Jussieu) Radlkofer: Growth
rings are present. Pores are rounded; the walls are
from 2p to 8p thick.
Vessel element length averages 428p, and ranges
from 245p to 560p, with a.MFR of 400p to 500p.
Vessel element end walls are inclined at an average
of 43 O, Vessel elements are generally ligulate.
Intervascular pitting comprises minute bordered
pits, ranging from 2p to 3p in diameter. Pit borders
are circular; pit apertures are lenticular and extend
beyond the pit borders.
Vessel to ray parenchyma pitting and vessel to
axial parenchyma pitting are very similar in appearance.
In both cases, the arrangement of pits in the
vessel wall is alternate and the pits are similar in
size and shape to intervascular pits. The vessel to
parenchyma pit-pairs (both types of parenchyma)
are half-bordered, with the simple pits of the parenchyma
wall ranging from circular to elongate, and
fenestriform.
The imperforate tracheary elements are septate,
most having two or more septa per cell. The cell
walls are 2p to 5, thick, and range from thin in
early wood to very thick in late wood. The average
length of the fibrous elements is 716p, and the range
is 440p to 1010p with a MFR of 630p to 800p. The
fibrous elements often contain starch.
Vascular rays are uniseriate and biseriate, the
latter type predominating. Uniseriate rays are generally
low, most are from 2 to 5 cells high. The biseriate
rays are somewhat higher, generally ranging
from 8 to 15 cells (250p). Upright cells are rare. Arrangement
of these cell types follows no pattern;
both procumbent and square cells occur in the same
horizontal rows. Procumbent cells predominate and
comprise the bulk of most rays. Most ray cells contain
a dark-staining, transparent to opaque substance
of unknown composition in addition to starch.
Axial parenchyma is present in both apotracheal
and paratracheal arrangement. Apotracheal parenchyma
is present in diffuse crystalliferous strands and
as banded and marginal parenchyma. The crystalliferous
strands are of frequent occurrence and range
up to 20 cells or more in height. Crystalliferous idioblasts
do not appear to be enlarged and each generally
contains a single prismatic crystal. Bands of
parenchyma may be up to 5 cells wide and are composed
of both crystalliferous and noncrystalliferous
strands. The bands may or may not be marginal and
are unevenly spaced. The arrangement of the paratracheal
parenchyma ranges from scanty vasicentric
to vasicentric.
All types of axial parenchyma cells frequently contain
starch and the dark-staining substance seen in
the ray cells. This dark-staining substance may also
occur in the vessels.
Hypelate trifoliata Swartz: Faint growth rings are
present. Pores are rounded, with walls varying in
thickness from 3p to 7p.
NUMBER 5 17
Vessel element length averages 319p, with a range
of 200p to 515p and a MFR of 275p to 400p. Vessel
element end walls are inclined at an average of 47'.
The vessel elements are generally ligulate.
Intervascular pitting comprises minute pits ranging
from 2p to 4p in diameter. Pit apertures are
rounded to oval and included within rounded to
polygonal borders.
Vessel to axial parenchyma pitting and vessel to
ray parenchyma pitting are similar in appearance.
Both are alternate to scattered in arrangement and
half-bordered, the pits in the vessel walls are similar
in size and shape to the intervascular pits.
The imperforate tracheary elements are nonseptate,
having walls which vary in thickness from
3p to 7p and range from thick to very thick, the
lumens of some cells entirely occluded. The average
length of the fibrous elements is 632p, with a range
of 420p to 850p and a MFR of 525p to 780p.
Vascular rays are uniseriate. The rays are heterocellular,
comprising procumbent, square, and upright
cells. The main body of most rays is composed
of square and procumbent cells, both frequently occurring
in the same horizontal row. Upright cells
are generally found in the marginal rows. The rays
range in height from 2 to 25 cells (350p) or more,
most rays are 10 or fewer cells high.
Axial parenchyma is present in both apotracheal
and paratracheal arrangement. Apotracheal parenchyma
is diffuse and comprises crystalliferous and
noncrystalliferous strands. The crystalliferous strands
range from 4 to 30 cells or more per strand, comprising
square idioblasts, each containing a single
prismatic crystal. Paratracheal parenchyma ranges
from vasicentric to aliform, with some confluent
present. A few of the paratracheal parenchyma
strands contain crystalliferous cells.
Sapindus saponaria Linneaus : Growth rings are
absent. The pores are circular and have walls from
2p to 5p thick.
Vessel element length averages 278p, with a range
of 120p to 390p and a MFR of 220p to 330p. End
walls are inclined at an average angle of 62'. In
general, the vessel elements are ligulate.
Intervascular pitting consists of minute pits, ranging
from 3p to 4p in diameter. The pit apertures are
oval to lenticular and included within rounded to
somewhat angular borders.
Vessel to both axial and ray parenchyma pitting
is alternate and half-bordered in nature. The
bordered to slightly bordered pits in the vessel walls
are very similar in size and shape to intervascular
pits, while the pits in the parenchyma walls are
large and simple.
Imperforate tracheary elements are septate, generally
having a single thin septum in each cell. Walls
vary in thickness from 2p to 4p and are thin in comparison
with the dimensions of the lumens. The average
length of fibrous elements is 911p, with a range
of 650p to 1180p and a MFR of 800p to 1100p.
Vascular rays are uni- to triseriate, with biseriate
and triseriate rays predominating. Rays are homocellular,
comprising only procumbent cells. The uniseriate
rays are generally short, from 2 to 10 or more
cells high. A few of the uniseriate rays, when seen in
tangential section, appear to be made up of some
enlarged square type cells. However, examination of
radial sections showed that, although some cells were
higher than other cells, they were nevertheless radially
elongate and thus procumbent. The biseriate
and triseriate rays are generally higher than the uniseriates,
ranging up to 50 cells (400p) or more in
height. Infrequently, enlarged marginal cells are in
the bi- and triseriate rays, but examination of radial
sections shows that these cells, although somewhat
larger, are still radially elongate. All of the rays frequently
contain large amounts of starch (starch
grains).
Axial parenchyma is abundant and confluent.
Whether this situation represents true confluent, that
is, paratracheal, parenchyma is difficult to determine,
for the bands of axial parenchyma are frequently so
wide as to occupy a large proportion of the groundmass
(Figure 18). These numerous, wide bands thus
surround most of the vessels (pores). It would be
impossible, without ontogenic studies, to say whether
this is fortuitous. The bands comprise two types of
strand parenchyma: strands of 2 to 4 axially elongate
cells, and strands of many cells, a large number of
these crystalliferous. The largely crystalliferous strand
parenchyma is commonly found at the margins of
the parenchyma bands. These strands were not seen
distributed among the fibrous elements. The crystalliferous
idioblasts are not enlarged. Distinctly vasicentric
parenchyma is also seen in which cells are
typically flattened and frequently disjunctive, forming
a complete sheath around each vessel or group of
vessels. These cells are distinct from the remainder
18 SMITHSONIAN CONTRIBUTIONS TO BOTANY
of the axial parenchyma because they contain the
same darkly stained substance found in the vessels.
Starch grains often occur in cells of the banded
parenchyma, but not in cells of vasicentric parenchyma.
SIMAROUBACEAE
Simarouba glauca DeCandolle : Growth rings are
absent. Pores are circular, with walls from 3p to 12p
thick.
Vessel element length averages 446p, with a range
of 270p to 560p and a MFR of 400p to 500p. Vessel
element end walls are inclined at an average of 60’.
Vessel elements are generally eligulate.
Intervascular pitting comprises small bordered
pits, ranging in size from 5p to 7p in diameter. Pit
apertures are oval and included within rounded to
somewhat angular borders.
Vessel to axial parenchyma pitting and vessel to
ray parenchyma pitting is similar in size, shape, and
arrangement. The pit-pairs are half-bordered, the
bordered pits of the vessel wall alternate and similar
in size to the intervascular pits. The simple pits of
the parenchyma are round to elongate, frequently
fenestriform.
Imperforate tracheary elements are nonseptate,
having walls which range in thickness from 1p to 3p
and vary from thin to very thin. The average length
of the fibrous elements is 794p, with a range of 550p
to 111Op and a MFR of 650p to 950p.
Vascular rays are uniseriate to multiseriate, with
biseriate and triseriate rays predominating. Infrequently,
the rays are up to five cells wide. All of the
rays are similar in size, although the uniseriates are
generally shorter than the bi- and triseriates. The
uniseriate rays range from 4 to 10 cells or more high.
The bi- and triseriate rays range from 5 to 30 cells
(400p) or more high. Rays are heterocellular, although
composed almost entirely of procumbent
cells: square cells are seen, but are infrequent in
occurrence and random in arrangement. The rays
cells frequently contain starch. Rays are storied
(Figure 23).
Axial parenchyma is present in paratracheal arrangement
as narrow, anastomosing confluent bands.
The bands are frequently continuous and range from
3 to 10 cells or more wide. Some of the bands are
discontinuous and, as such, constitute an aliform configuration
with long “wings.” Axial parenchyma comprises
strands generally consisting of four cells each.
The strands tend to be storied. (Figure 23). Crystalliferous
strand parenchyma is also present, each
strand consisting of 5 to 10 or more cells. The
crystalliferous idioblasts are rectangular, nonenlarged
cells, each containing a single optically anisotropic
prismatic crystal. Axial parenchyma cells that are in
contact with vessel elements are generally flattened
and frequently disjunctive. Cells in strand parenchyma
frequently contain starch.
Suriana maritima Linnaeus: Growth rings are absent.
Pores are circular, with vessel element walls
ranging in thickness from 2p to 6p.
Vessel element length averages 173p, with a range
of 45p to 230p and a MFR of 165p to 200p. Vessel
elements are generally eligulate.
Intervascular pitting comprises minute bordered
pits ranging in size from 3p to 4p in diameter. Pit
apertures are lenticular to oval and are included
within or are extended slightly beyond the rounded
to somewhat angular borders.
Vessel to axial parenchyma pitting and vessel to
ray parenchyma pitting are similar in size, shape, and
arrangement. The pit-pairs are half-bordered and
alternately arranged. The bordered pits of the vessel
elements are similar to intervascular pits, while the
simple pits of the parenchyma (both ray and
axial) are frequently large, oval to elongate, and
fenestriform.
Imperforate tracheary elements are nonseptate,
having walls which vary in thickness from 2p to 6p
and range from thin to thick. Some of the fibrous
elements in Stern @ Briticky 230 are gelatinous and
in Stern @ Brizicky 230 and Stern 2666 they contain
a darkly staining, translucent to opaque substance of
unknown composition. The average length of the
fibrous elements is 586p, with a range of 335p to
780p and a MFR of 460p to 700p.
Vascular rays are uni- and biseriate, with the
uniseriate rays predominating. Rays make up a large
portion of the groundmass as viewed in longitudinal
section. Rays are heterocellular, comprising mainly
upright and square cell types, the procumbent cell
type occurs infrequently. Arrangement of the various
cell types is random. Both the uniseriate and the
biseriate rays are short, generally ranging from 3 to
15 cells or more in height. All of the ray cells conNUMBER
5 19
tain the dark-staining substance found in the fibrous
elements.
Axial parenchyma is present in both apotracheal
and paratracheal arrangement. Apotracheal parenchyma
is diffuse and diffuse-in-aggregates and comprises
noncrystalliferous strands consisting of two cells
or more per strand. The paratracheal parenchyma
is scanty vasicentric to vasicentric, and frequently
comprises disjunctive cells. Both types of axial parenchyma
cells contain the same dark-staining substance
present in the fibrous elements and the ray
cells. An anastomosing arrangement of cells containing
this substance is seen in transverse section
and comprises primarily the diffuse-in-aggregates
apotracheal parenchyma and rays.
Vessel elements frequently contain either this darkstaining
amorphous substance, or a granular substance,
which is similarly stained. Those vessel elements
with empty lumens frequently have their cell
walls coated with this dark-staining substance.
Discussion
Since structures which tend to be easily modified in
response to environmental changes are of relatively
little taxonomic importance, the choice of characters
to be studied is critical. In this respect, the components
of mature secondary xylem tissue are considered
relatively implastic, especially when compared
with characters of external morphology (Metcalfe
and Chalk 1950). Of the large number of anatomical
characters discernible from study of mature secondary
xylem, however, certain characters appear
to be more plastic than others. Characters incorporating
dimensions are, in general, more apt to
vary with change in environment and growing conditions.
The presence or absence of growth rings, the
lengths of fibrous elements, and the number of vessels
per unit area are examples of plastic characteristics
which are usually of little taxonomic significance. On
the other hand, characters of form or arrangement
are often less plastic and therefore more significant
taxonomically. As examples of these, one may cite
the arrangement of intervascular pitting, the organization
of axial parenchyma, and the configuration
of perforation plates.
In addition to the relatively implastic nature of
the anatomical characters of wood, the structure of
wood tends to be evolutionarily more conservative
than features of external morphology (Metcalfe and
Chalk 1950). As a result, differences in the wood
structure are inclined to be less dramatic than are
differences in external morphology. Thus, Metcalfe
and Chalk state that ". . . this [the implastic nature
of wood structure], combined with its more conservative
nature, adds to its value for the study of larger
groups."
In addition to being taxonomically valuable as a
basis of classification, anatomical variations in secondary
xylem may reflect the phylogenetic status of
plant taxa. Although vessel element length may vary
greatly within different plants of the same species
and even within the tissues of the same plant, depending
upon the age and position of the tissue
studied (Bailey and Tupper 19 18), vessel element
length is the most accurate reflection of the fusifom
cambial initial length (Chalk and Chattaway 1934).
Bailey and Tupper correlated fusiform cambial initial
length, as reflected by the length of vascular elements,
with degree of evolutionary development
based on both fossil and extant plants. They found
that Calamitales, Lepidodendrales, and Cycadofilicales,
in addition to extant vascular cryptogams,
possessed the longest tracheary elements ; gymnosperms,
both extant and extinct, possessed tracheary
elements of intermediate length; and extant dicots
had the shortest vascular elements. From this classic
work, based on a large number of plants of wide
distribution within the extinct and extant tracheophytes,
one is led to conclude that a reduction in
lengh of fusiform cambial initials is associated with
evolutionary advance (specialization) .
Frost ( 1930a, 1930b, 1931 ) , Bailey and Tupper
(1918), Kribs (1935, 1937), and others correlated
the lengths of the fusiform cambial initials with other
features of dicotyledonous xylem anatomy. They concluded
that definite trends of specialization accompanied
the evolutionary reduction in length of the
fusiform cambial initials.
Thus, the systematist, if he so chooses, has at hand
a tool of great potential taxonomic importance. Using
characters derived from the study of wood anatomy
as correlative and complementary information,
he has an independent means of testing presumptive
phylogenetic relationships. These means are not
based on the circuitous reasoning commonly encountered
in classification based only on morphological
characters, e.g., a plant is considered primitive
SMITHSONIAN CONTRIBUTIONS TO BOTANY
because it possesses a primitive flower type, which
itself is considered primitive because it is characteristic
of a “primitive” taxon. The seemingly unrelated
characters of perforation type, end wall inclination,
intervascular pitting, etc., are now recognized as
constituting a syndrome or correlative complex useful
in reflecting not only form relationship, but the
evolutionary status of the plant. As Bailey (1957)
stated, “The chief trends of evolutionary specialization
in the cambium and xylem of dicotyledons are
now so reliably established (except in the case of
certain patterns of wood parenchyma distribution)
that they can be utilized to advantage in studying
salient problems of phylogeny and classification.”
A final point must be made on the value of xylem
anatomy in the overall scope of classification. In itself,
xylem anatomy is of little inherent value to the
taxonomists. Bailey (1953) stated that wood structure,
as a collection of internal or endomorphic
characters, is “. . . inherently no more conservative
or reliable than are exomorphic ones.’’ Any given
structure or character is not universally plastic or
implastic; a character which may be implastic and
thus of taxonomic value within one group of plants,
may be quite variable and thus of little use in
another. Thus, endomorphic xylem characters of
and by themselves, are of no more intrinsic value to
the taxonomist than are exomorphic characters.
However, when used in conjunction with other data
derived from external morphology, in addition to
other areas of study, xylem anatomy can be of significant
value. When utilized by itself, xylem anatomy
best serves the taxonomist as a means of negation
of relatedness among taxa (Bailey 1957, Cronquist
1968). Because of the ever-present possibility
that similar structures may result through parallel
evolution, xylem characters alone cannot be considered
as indicative of positive relationship without
the strong support of supplemental data.
A brief comparison of the anatomical features of
the taxa included in this study follows. In general,
these anatomical features conform well with those
previously reported in the literature. Some discrepancies
are indicated below.
The single observation of an apparent multiple
perforation plate in Metopium toxiferum is unique
in that all other perforations observed in this study
are simple. Although at least two genera of Anacardiaceae
are reported in the literature (Metcalfe
and Chalk 1950, Heimsch 1942) as having multiple
perforations in addition to simple perforations
( Campnosperma and Heeria) , Metopium is reported
as possessing only simple perforations (Heimsch
1940). If the perforation observed is indeed a multiple
perforation and not a collection of fenestriform
vessel to parenchyma pits clustered at the end of the
vessel (as suggested in the description), the occurrence
of such multiple perforations is extremely infrequent.
Either interpretation leads one to conclude
that, for all intents and purposes, the xylem of
Metopium is characterized by simple perforations.
My observation that Toxicodendron radicans has
diffuse-porous wood raises some questions. The genus
Toxicodendron is reported (Heimsch 1942, Metca’fe
and Chalk 1950, Record and Hess 1943) as having
generally ring-porous wood. Is the diffuse-porous
wood of Stern 2633 (Figure 19) a result of environmental
factors, or is it simply a feature of immature
tissue? As noted in the description, the outer growth
rings exhibit a tendency toward ring porosity. On the
Florida Keys, T. radicans never has stems that even
approach the robust stems of this species growing in
northeastern United States. It is possible that the depauperate
growth of the stem on the Keys may have
some bearing on the formation of ring porosity. The
climate of the Keys is probably conducive for p!ant
growth throughout the year. This in itself will have
an influence on the formation of growth rings and
may seriously affect the expression of typical ring porosity
in this species as it occurs on these islands.
Spiral thickenings are not present in the vessel elements
of T. radicans, although all memberss of the
genus Toxicodendron are reported (Record 1939)
as having this feature. Heimsch (1940) reports the
presence of spiral thickenings in the small vessel
elements of only T. uernix and the Asiatic T. trichocarpum.
Heimsch notes, as a possible explanation
of this discrepancy, that the portions of the vessel
element wall occurring between the slitlike intervascular
pits and the fenestriform vessel to parenchyma
pits give the impression of spiral thickenings
in unstained or poorly stained sections. My observations
agree with those of Heimsch to the extent that
no spiral thickenings were seen in the specimen of
T. radicans.
* Record’s description of the wood characters of the
genus Toxicodendron is based on specimens of T. diversiloba,
T. radicans, and T. vernix.
NUMBER 5 21
Striking similarities occur among Metopium toxiferum,
Toxicodendron radicans, and Bursera simaruba.
These s;ecies have fenestriform vessel to parenchyma
pit-pairs (Figure 32). Metopium toxiferum
and Bursera simaruba have medium-sized (in diameter)
intervascular pitting. Other species of Pinnatae
studied have vessel to parenchyma pitting which is
very similar structurally to the intervascular pitting,
the intervascular pits ranging in size from small
to minute in diameter. Metopium toxiferum and
Bursera simaruba have horizontal intercellular canals
in their rays (Figure 24). Record (1939) notes that
these canals occur in Toxicodendron diversiloba,
although Heimsch (1940) did not observe radial
canals in any members of the genus. Rays in Metopium
toxiferum, Bursera simaruba, Swietenia mahagoni,
and the two species of Zanthoxylum are so
similar as to be hardly distinguishable, except for
the occurrence of intercellular canals.
Field collection of the two species of Zanthoxylum
points up an obvious difference between Z. fagara
and Z. flavum. Although Z. flavum is reported in the
literature as possessing wood (heartwood) which is
". . . exceedingly hard and heavy" (Small 1933),
having ". . . sp. gr. .90, 56 Ibs./cu. ft." (Record and
Hess 1943), hand sawing showed that, of the two
species, Z. fagara was much harder. Upon study of
the sections of Z. flavum, I was surprised to note
the presence of thick-walled fibers and a small
amount of axial parenchyma (as compared with
Z. fagara, Figures 14, 15), certainly not what one
would expect of the very soft wood Z. flavum proved
to be on sawing. Observation of transverse sections
under crossed nicols reveals, however, that the secondary
wall thickenings of the fibrous elements
of Z. flavum are optically inactive, while those of
Z. fagara are optically active. This indicated that,
although the secondary walls of the fibrous elements
of Z. flavum are lignified (take up safranin stain
readily), the orientation of the cellulose micelles of
these secondary walls is such that polarized light
is not refracted in the transverse plane of section.
Although not typical in appearance, one could refer
to these fibrous elements as gelatinous, owing to the
apparent noncrystalline nature of the secondary wall
thickenings. The wide occurrence of gelatinous fibers
could explain the softness of the wood in Z. flavum.
A character which separates members of the Rutaceae
from the other Pinnatae is the presence in
the rutaceous taxa of at least some radial chain pore
arrangement (Figure 15). In other Pinnatae, the
radially oriented pore groups comprised only radial
multiples (Figure 12). All members of the Rutaceae
have banded and diffuse axial parenchyma in addition
to some paratracheal parenchyma. Swietenia
mahagoni, Metopium toxiferum, and several members
of the Sapindaceae also have this combination of
axial parenchyma arrangements. Amyris and Citrus
have enlarged crystalliferous idioblasts (Figure 25),
as does Dodonaea of the Sapindaceae. The occurrence
of crystals in either ray parenchyma or axial
parenchyma is a nearly universal character of the
species studied. Only Metopium toxiferum, Toxicodendron
radicans, and Suriana maritima lack such
crystals.
Although the xylem anatomy of Cardiospermum
halicacabum is not described in the literature
(Heimsch 1942, Metcalfe and Chalk 1950, Record
and Hess 1943), the xylem of two genera (Serjania
and Paullinia) of sapindaceous lianas are described.
The occurrence of two distinct vessel element types
in Cardiospermum (Figure 35) noted above conforms
with the descriptions of vessel elements given
for Serjania and Paullinia (Heimsch 1942, Metcalfe
and Chalk 1950). The presence of dimorphic vessel
elements is likely related to the lianous habit in this
family.
Throughout this investigation, various anatomical
characteristics were evaluated, with the hope that1
a significant set of these could be found which might
reflect the present familial arrangement of the 16
species studied. Although certain families did possess
anatomical features which served to identify their
members, other families did not possess such unifying
features. However, all the members of Pinnatae
do exhibit many anatomical characters in common
to indicate that we are dealing with a remarkably
homogeneous group of plants.
Comparison among families of Pinnatae of those
anatomical characters considered to be of greatest
taxonomic and phylogenetic significance by Metcalfe
and Chalk (1950) reveals that (1) all members
possess vessel elements having simple perforations,
(2) the vessel elements of all members have alternately
arranged intervascular pitting, (3) all members
possess fibers with slitlike simple to slightly
bordered pits, and (4) all members possess at least
paratracheal axial parenchyma, with the banded
22 SMITHSONIAN CONTRIBUTIONS TO BOTANY
configuration (paratracheal and apotracheal) the
most common. Although anatomical differences exist
among the 16 species studied, none of these is great
enough to warrant the exclusion of any one of the
members from this group. By and large, greater
anatomical differences are seen to exist among genera
within the same family (e.g., Sapindaceae-
Table 4) and even among species of the same genus
(e.g., Zanthoxylum-Table 4), than exist among
the families represented in this group.
Although the ray structure encountered in this
study varies in regard to cellular makeup (heterocellular
as opposed to homocellular, uniseriate as
opposed to multiseriate) , the relative sizes of the
rays of each species are similar. The rays of species
having only uniseriates are low, rarely exceeding
2OOp in height. Those rays in species having multiseriates
are also low, rarely exceeding 600p in height.
The widest multiseriate rays do not exceed 10 cells
( l o o p ) in width.
Looking at anatomical characters which vary
within the group as a whole, but remain relatively
constant at the family level, we find an interesting
and significant segregation. The nature of the vessel
to parenchyma (both axial and ray) pitting is remarkably
consistent among the 15 genera, with the
three exceptions of Bursera, Metopium, and Toxicodendron.
Only Bursera and Metopium of the 15
TABLE 4.-Summary of xylem anatomical data in the "Pinnatae"
SPECILS
ANACAFDIACEAE
Metapiir. toxife?wi
Toxicade?.dron radicans
BURSEFACEAE
B~rsera sisaruba __-
TZLIACFAE
Swietenia mhegoni
RUTACEAE
Amyris elernifera
Citm6 a u r a n t i i f o l i a
Zanthaxyllun
2. fl8"Ul
SApINDACEbi
_ -
Cardiospemm halicesabm
Cupacia glabra
Jkdanaea viscose ~ _ _
panim1ata
m e l a t e trifoliata
Sepindus sapoIia?ia
SDNLROUBACEAE
Simmuba glauca
Suriana maritima --
42 4 u
ri
y 1 1
> .5
L,
4:
;2
-
375
253
531
'137
25c
273
261
515
200
414
234
426
319
278
446
173 -
-
ELEK -
ci
J
u
r i a
OJri m a c
Loo m a
G I -
>d
2:
? $
m a -
4ir
41
48
62
55
58
64
44
76
44
54
43
'17
62
6c
63 -
-
S -
i
ri a
n"
42
3 . 4
5
:%
u r N i
.i 0 ) - -
medim
Small
rnediwr.
nin-te
sinute
srnE.11
minute
small
small
minute
minure
minute
minute
m.ir.use
small
minute
B, A l , C
D, s, v
S
B, #, S, 'J
C, A1
D, s, v
1 , 2 , 1 , ~ het
1, horn.
L,3,ZnL, het
L 3 3 , h e t .
1 , 3 3 , h e t .
'Classification of intervascular p i t t i n g follows that swgested by Record snd Chattaway (19?9).
bUnderlined nurr.bers indicate the predominant ray type (2 = tPiEeriste rays most freqilent ).
*Xembers having Septate fibrous elements which contain starch.
NUMBER 5 23
genera possess intervascular pits of medium size, the
other 13 genera have either small or minute pits.
Four genera possess heterocellular multiseriate rays
having uniseriate wings, and among them are Bursera
and Metopium. Add to this the horizontal intercellular
canals in the rays of both Bursera and Metopium,
and one recognizes that the members of the
Florida Keys Pinnatae may be subdivided on the
basis of xylem anatomy so that the genera of Anacardiaceae
and Burseraceae are by and large distinguishable
from the other genera.
Phylogenetic interpretation of the data derived
from this study indicates that the woods of the 16
species exhibit a high degree of specialization. The
syndrome of short to medium length vessel elements,
simple perforation plates, alternate intervascular pitting,
and absence of steeply inclined vessel element
end walls shows that the members of the Pinnatae
studied are at approximately the same relatively
advanced level of specialization. In addition, the
storied structure, found in Simarouba and Swietenin
(Figure 23), represents another line of specialization
which occurs only in certain Pinnatae. Kribs (1935)
considered woods having either homocellular rays
(Amyris and Sapindus) or strictly uniseriate rays
(Amyris, Cupania, and Hypelate) as highly advanced.
The rays of Suriana are, for all intents and
purposes, uniseriate. Heterocellular rays which are
made up in large part of procumbent cells, with
the square and upright cells, or both, occurring only
sporadically and infrequently (Citrus and Simarouba)
, are also considered as relatively advanced.
The common ray configuration (procumbent cells
comprising the multiseriate portion with upright'
and square uniseriate wings or both) seen in Metopium,
Bursera, Swietenia, and Zanthoxylum, in addition
to the low rays found in the remainder of
the genera, constitutes an advanced ray situation.
The presence of various aggregate arrangements of
axial parenchyma, such as banded, aliform and
confluent, or both (only Toxicodendron, Bursera,
and Suriana lack such arrangements), is accepted
as being advanced. The occurrence of fibrous elements
lacking distinctly bordered pits is also an
advanced characteristic.
The wide occurrence of starch grains in the parenchymatous
tissue of the specimens studied probably
is of little taxonomic significance. However,
specimens of Toxicodendron, Bursera, Exothea, and
Cardiospermum have septate fibrous elements that
contain this storage product (Figures 12,13,24,29) .
This feature may be of some taxonomic import in
that it is correlated with a relatively small amount
of axial parenchyma in these taxa. This observation
is in agreement with those of Harrar ( 1946).
The occurrence of septate fibrous elements appears
to be a local phenomenon and is of little taxonomic
significance in this group (the Pinnatae) . The only
families that have members lacking septate fibers,
based on the species in this study, are Rutaceae and
Simaroubaceae. Both of these families, however, have
other members that have septate fibers (Metcalfe
and Chalk 1950).
The taxonomic value of diffuse-porosity is also
questionable, The effect of environment on the
topography of wood is not certain. The great majority
of tropical trees having distinct growth rings
possess woods that are diffuse-porous, and the OCcurrence
of ring-porosity is largely restricted to woody
plants of the North Temporate Zone (Gilbert 1940).
The fact that all members, with the possible excep-,
tion of Toxicodendron, have diffuse-porous wood is
thus of debatable taxonomic value here.
A survey of the literature (Metcalfe and Chalk
1950), concerning both morphological and anatomical
characteristics of the families concerned with in
this study, shows that the occurrence of secretory
structures (Figures 24-27) characterizes members
of the Pinnatae. The intercellular canals of anacardiaceous
and burseraceous woods, and the intercellular
canals in the bark and pith of these families,
as well as Simaroubaceae and Sapindaceae, are
examples of such structures. Secretory cells are reported
as occurring in the pith and cortex of all
families. The occurrence of pellucid glands in the
leaves of Rutaceae is well known. In addition, traumatic
axial canals are reported to occur either frequently
or sporadically in some members of all families,
with the exception of Sapindaceae and Anacardiaceae.
The widespread presence of dark-staining,
gumlike substances in the parenchyma and
vessels of many of the species seen in -this study
(Figures 20,22) suggests the secretory potential of
these members. The traumatic axial canal observed
in Zanthoxylum fagara also contained a darkly staining
deposit. Crystals, which occur widely in the
xylem of Pinnatae are products of idioblasts. These
too are considered as secretory cells. Thus, the ocSMITHSONIAN
CONTRIBUTIONS TO BOTANY
currence of secretory structures in most, if not all
members, may be of taxonomic value; insofar as it
might serve as another indication of the homogeneous
nature of Pinnatae.
The data derived from this study indicate that
the Pinnatae constitute a homogeneous group, and
that no anatomical basis exists for segregation of the
various members into separate orders. The traditional
Englerian separation of the Sapindaceae and Anacardiaceae
from the remainder of the families is not
supported by xylem anatomy. Hutchinson’s separation
of the families into three orders, and Takhtajan’s
and Thorne’s separation of Sapindaceae from
the other families, likewise, have no anatomical basis.
Cronquist’s treatment most nearly reflects the anatomical
similarities that exist, with the exception
that he removes Suriana from the Simaroubaceae
and places it into the Stylobasiaceae. There is no
anatomical foundation for the separation of Suriana
from the Simaroubaceae. This conclusion is based
both on data derived from this study and the anatomical
literature (Webber 1936). Cronquist’s (1968)
assignment of Suriana and Stylobasium to his Stylobasiaceae
is based on characters of habit and morphology,
and a complete study of the anatomy of
Stylobasium and Suriana must be carried out before
such an association can be anatomically evaluated.
The inclusion of Anacardiaceae and Burseraceae in
the single family Terebinthaceae, as proposed by
Hallier (1912), is supported by xylem anatomy.
Summary
A study of the wood of 16 species of Florida Keys
Pinnatae indicates that the group is anatomically
homogeneous. All members possess simple perforation
plates, vessel elements having alternate intervascular
pitting, fibrous elements with small slitlike,
simple to vestigially bordered pits, and axial parenchyma
which is both apo- and paratracheal.
Crystals are of wide occurrence in the parenchyma
cells, and banded and aliform to confluent parenchyma
occur in several taxa. Certain families or
groups of families have unique characters : radial
chain arrangement of pores in the Rutaceae, random
arrangement of cells in the heterocellular ray types
among members of the Sapindaceae, and fenestriform
vessel to parenchyma pit-pairs and intercellular canals
in the rays of Anacardiaceae and Burseraceae.
The only separation of families within Pinnatae
suggested by a syndrome of several unique characteristics
is the formation of an Anacardiaceae-Burseraceae
complex. These characteristics, however,
when viewed in light of the many common features
of the families, are not sufficient bases for the separation
of the Anacardiaceae and Burseraceae from
the Pinnatae as a group.
There is no anatomical basis for the separation
of families into distinct orders as proposed by Engler,
Hutchinson, Takhtajan, and others. The system of
classification proposed by Cronquist is anatomically
feasible except for his exclusion of Suriana from the
Simaroubaceae. The members of the Pinnatae are
seen by this author as belonging to a taxon corresponding
well with Cronquist’s Sapindales.
Phylogenetically, the Pinnatae constitutes an advanced
taxon. Simple perforation plates, short to
medium length vessel elements having alternate intervascular
pitting, slightly inclined vessel element
end walls, advanced ray types, fibrous elements with
simple or vestigially bordered pits, and the predominant
banded and confluent axial parenchyma mark
the Pinnatae anatomically as a highly specialized
group. The possession of storied rays in two species
is another trend of specialization.
Based on the data derived from this anatomical
study and from the literature, the 16 species of
Florida Keys Pinnatae are members of a homogeneous,
phyletically advanced group. Furthermore, that
this group constitutes a genetically related complex
of plants is borne out by correlative studies in floral
and vegetative morphology, as well as by the substantial
anatomical studies of which this investigation
is a part. These members belong in the Sapindales
as described by Cronquist.
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NUMBER 5
FIGURE 1-4-1, Toxicodendron radicans: habit showing flowers; 2, Bursera simaruba: habit
indicating size of tree; 3, Bursera simaruba: leaves and fruit; 4, Swietenia nahagoni: habit indicating
size of tree.
27
28 SMITHSONIAN CONTRIBUTIONS TO BOTANY
FIGURES 5-8.-5, Zanthoxylum flavum: leaf showing glandular dots; 6, Sapindus saponaria:
habit with fruits and leaves (note winged rachis of pinnately compound leaves) ; 7, Sapindus
saponaria: fruits; 8, Cardiospermum halicacabum: habit with fruits and flowers.
NUMBER 5
FIGURES 9-1 1.-9, Cupania glabra: fruits and leaves; 10, Simarouba glauca: flowers; 11,
Suriana maritima: flowers (note simple leaves).
29
30 SMITHSONIAN CONTRIBUTIONS TO BOTANY
FIGURES 12-15.-12, Bursera simaruba: transverse section showing radial multiples and solitary
pores (note starch in the fibers), X 246; 13, Bursera simaruba: transverse section viewed
under crossed nicols (polarized light) showing the birefringent property of the cell walls and
starch grains, X 269; 14, Zanthoxylum fagara: transverse section showing banded parenchyma
and radially oriented pore multiples and chains, X 269; 15, Zanthoxylum fiavum; transverse
section showing large amounts of thick-walled fibers. Banded parenchyma and radially oriented
pore multiples and chains are also shown (note the presence of starch grains in both ray and
axial parenchyma), X 269.
NUMBER 5 31
FIGURES 16-19.-16, Cupania glabra: transverse section showing growth rings, and solitary,
radial multiples, and clusters of pores, X 109; 17, Simarouba glauca: transverse section showing
aliform and confluent parenchyma arrangement, X 97 ; 18, Sapindus saponaria: transverse
section showing confluent bands of parenchyma, X 97 ; 19, Toxicodendron radicans: transverse.
section showing qdestionable diffuse-porous distribution of pores, X 246.
32 SMITHSONIAN CONTRIBUTIONS TO BOTANY
FIGURES 20-23.-20, Cupania glabra: radial section showing randomly arranged procumbent,
square and upright cells. Note the gumlike substance in ray cells, X 390; 21, Metopium
toxiferum: Tangential section showing rays having uniseriate “wings,” X 246; 22, Swieteniu
mahagoni: Radial section showing rays having square and upright, or both, marginal cells, X
97; 23, Simarouba glauca: tangential section showing the storied arrangement of rays and axial
strand parenchyma, X 97.
NUMBER 5 33
FIGURES 24-27.-24, Bursera simaruba: tangential section showing intercellular canals in the
rays (note the starch grains in the septate fibers), X 269; 25, Citrus aurantiijolia: radial section
showing enlarged crystalliferous idioblasts, X 539 ; 26, Zanthoxylum fagara: Transverse
section showing traumatic intercellular canal, X 269 ; 27, Zanthoxylum fagara: radial section
showing the traumatic intercellular canal in longitudinal section, X 539.
34 SMITHSONIAN CONTRIBUTIONS TO BOTANY
FIGURES 28-32.-28, Exothea paniculata: radial section showing slitlike simple to slightly
bordered fiber pits in face view (arrow), X 1872; 29, Exothea paniculata: tangential section
showing the fiber pits in transverse section (arrow). Note starch grains, X 1872; 30, Citrus
aurantiifolia: tangential section showing alternate intervascular pitting. Note the coalescence
of adjacent pit apertures (arrow), X 734; 31, Metopium toxiferum: tangential section showing
unilaterally compound intervascular pittings (arrow), X 1872 ; 32, Bursera simaruba:
maceration showing the occurrence of fenestriform vessel pitting. These pits occur in the cell
walls of both vessel elements and parenchyma. Note the simple perforation plate, X 269.
NUMBER 5 35
FIGURES 33-35.-33, Amyris elmifera: radial section showing tyloses and granular, translucent
material in the vessel elements, X 292; 34, Metopium toxijerum: transverse section showing
tyloses in vessels and the occurrence of gelatinous fibers, X 269; 35, Cardiospermum halicacabum:
transverse section showing large solitary pores and radial multiples of small angular
pores (arrow), X 269.
* U.S. OOVERNMCNT PRlNTlNQ OFFICE: 1972-417--398/12