QUESNEL, Dieudonne-Gabriel Louis, (kay-Eel), South American botanist, born near Cayenne in 1749; died in Cayenne in 1801. He received his education in France, served for several years in the army, and fought at Tobago in 1780. After the conclusion of peace he returned, with the brevet of major, to his estate in Guiana, and, at the suggestion of Malouet (q. v.), established a model farm, and adopted new methods of cultivation. For several years he carried on his agricultural experiments, but, unwise management proving detrimental to his fortune, he abandoned agriculture and became a traveller. He explored French Guiana and the northern provinces of Brazil, and formed an important herbarium, which is now deposited in the museum of Cayenne. Among his works are "Iterbier explique des plantes de la Guiane" (2 vols., Cayenne, 1792); "Description de la flore Guianaise" (1795) ; and "Journal de voyage a tra-vers les Pampas" (1796).