KOEHLER, Alexander Daniel (kuh-ler), German botanist, born in Altenkirchen, Rugen island, 18 April, 1762; died in Langenbranden, Wurtemberg, 6 December, 1828. He inherited from his father an independent fortune, and occupied himself with botanical studies. A letter from Alexander yon Humboldt, then in America, determined him to make that country the field of his studies for several years, and he went in 1801 to Santa Fe de Bogota, and was for seven years a collaborator of Jose Mutis, the Spanish botanist. On his suggestion, Mutis established in 1801 an astronomical observatory in Santa Fe. and Koehler provided it with valuable instruments. After the death of Mutis in 1808, he resolved to finish part of the latter's work, and, going to Brazil, made a thorough study of the palm-trees of that country. The civil wars that desolated the northern part of South America at that time put a stop to his explorations, and, passing to Peru, he visited that country, studying also the political institutions of Chili before returning in 1816. He devoted the remainder of his life to the publication of the materials he had collected during his travels, and read several papers before the academies of sciences of Munich and Berlin, of which he was a corresponding member. He kept up also a correspondence with Humboldt, and furnished him with notes and information which the explorer utilized in the revised edition of his travels through America. Among his works are "Reise nach Brasilien" (Stuttgart, 1817); "Wanderungen in Peru und Chile" (2 vols., 1818); "Karte yon dem panamischen Isthmus " (Munich, 1821);" Flora Brasiliensis " (4 vols., Berlin, 1821-'3); "Flora Venezuliensis" (4 vols., 1822); "Studien fiber den offentlichen Unterricht in Chile" (Stuttgart, 1823); " Reisen dureh Nordwest-Venezuela " (Leipsic, 1824); "Genera et species pahnarum" (Stuttgart, 1825); "Sertum Peruanum" (2 vols., Berlin, 1826): "Institutiones botanicae" (Stuttgart, 1827); and "Conspectus polygalorum florin Brasilicae meridionalis" (2 vols., Berlin, 1827).