Monographs Details: Oncidium nigratum Lindl. & Paxton
Authority: Schweinfurth, Charles. 1967. Orchidaceae of the Guayana Highland. Mem. New York Bot. Gard. 14: 69-214.
Description:Distribution and Ecology - VENEZUELA. Bolivar: Mt. Roraima, 1700-2000 m alt., Schomburgk s.n. (type of O. nigratum), D. Burke, Im Thurn 114; Ptari-tepui, terrestrial on forested south-facing slopes overlying sandstone, on "Cave Rock" above "Cave Camp," 1810 m alt., flowering stems erect-ascending or arching, sepals and petals wavy-twisted, brown-banded alternating with creamy white, recurved at the tip, lip chiefly yellow with dull orange plaits below, crests or appendages in center deep yellow and orange, October 29, 1944, J. A. Steyermark 59488; Cerro Uaipdn, 1600 m alt. (F. Cardona) L. Schnee 723 (type of O. uaipanense); Chimanta Massif, on plateau of southeast-facing upper shoulder of Apdcara-tepui, 2000 m alt., terrestrial around boulder in elfin forest formation, pseudobulb ancipitous, rigid, leaves coriaceous, grass-green above and paler beneath, pedicels slender, arched, 0.5 mm thick, sepals and petals white "with 2 or 3 large patches of dull purple in upper half, lip pale yellow with dull madder-purple patches on the side and toward the tip, aest pale yellow with madder-purple dots, June 19, 1953, Steyermark 75734; Chimantd Massif, Central Section, along edge of escarpment by Middle Falls of Rfo Tirica below Summit Camp, 1925 iii alt., terrestrial in exposed rock crevices, pseudobulb somewhat flattened, leaves coriaceous, olive green above and dull gieen beneath, scape brown-lavender, sepals and petals with cream-colored tips and commonly blotched with cliocolate from the base to below the middle, lip 3-lobed, lateral lobes strongly reflexed, subhorizontal, deep yellow, mid-lobe descending, pale yellow mottled with pale brown in the center, crest yellow with brown spots and with irregular acute protuberances, column erect, white, yellow and brown, February 5, 1955, J. A. Steyermark & J. J. Wurdack 454; same locality, swampy savanna in depression along tributarv valley of east branch of headwaters of Rio Tirica. 2120 m alt., terrestrial, pseudobulbs ancipitous, olive, leaves erect, subcoriaceous, grass-green above and paler beneath, sepals and petals cream-white "with dark purple blotches, lip yellow with band (2-3 mm wide) of chestnut brown, crest yellow with magenta dots, column yellow, basally white, February 13, 1955, Steyermark & Wurdack 840; Auydn-tepui (G. Steinheil), G. C. K. Dunsterville 682; same locality, cumbre de la parte sureste: entre "Boggy Camp" (primera quebrada con agua al norte de "Libertador") y "Oso Woods Camp,'' 2200 m alt., terrestrial on open rocky exposures, pseudobulbs tawny-yellow, compressed, leaves erect, rich green above and yellow-green beneath, sepals and petals sordid white with dull brown bands, lip descending, golden "with brown transversing lower appendage," column white with dull spots and golden at the apex. May 1, 1964, J. A. Steyermark 93196.
Cyrtochilum nigratum Kranzl., Pflanzenr. IV. 50, 2(80) : 74. 1922.
Oncidium uaipanense Schnee, Rev. Fac. Ing. Agr. Maracay 1: 118, t. (opp. 120) . 1952.
Distribution:Venezuela South America