Biographies of American Seedsmen and Nurserymen Downing, Andrew Jackson–(1815-1852)–Newburg, New York–Downing and his brother Charles Downing operated the Downing Nursery at Newburg, New York.  They specialized mostly in fruits.  Their father was a nurseryman as well.  Andrew Jackson  was America’s most influential landscape gardener of the period.  In 1841 he published his Treatise on the Theory and Practice of Landscape Gardening when he was twenty-six years old.  It was the first, and still one of the best American books on the subject, and has had a greater influence on American horticulture than any other similar volume.  His book Cottage Residences also appeared in 1841, and in 1845, with his brother Charles, he published simultaneously in London and New York the book Fruits and Fruit Trees of America.  In 1846, he became an editor of The Horticulturist.  In 1850 he visited the great estates of England, and saw for the first time the landscape gardening of Europe.  In 1851 he was chosen to lay out the grounds of the Capitol, the Smithsonian Institution and the White House, in Washington, D. C.,  but he died before the project could be completed.  He died by drowning on July 28, 1852 when the steamer, Henry Clay, caught fire on its voyage to New York City.  He was the first great American practitioner of what was known as the English or natural school of landscape gardening.  He gave inspiration to Frederick Law Olmsted, the next great genius in American landscape gardening.
Sources:  Plants; Woodburn2; Bailey; PHS2; CHSJ-Apr. 1966; HG; Elliott; VanRav