Pleurothallis obscura A. Rich. & Galeotti 1845 SUBGENUS Acianthera SECTION Brachystachyae Lindley 1859

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Common Name The Dark Pleurothallis

Text by Jorge Melendez

Plant epiphytic, small, shortly repent to caespitose, the secondary stem terete with 2-3 tubular sheaths below, shallowly channeled above, 6-10 cm long, Leaf thickened, very narrowly ovate to linear, acute tridenticulate, sessile, 7-11 cm. Inflorescence a fascicle of a few (2-3), short 2 to 3 flowered racemes; peduncles stout about 5 mm long, from the axil of the leaf; spathe about 3 mm long. Flowers small, bilabiate, fleshy, orange, externally sparsely verrucose; floral bract infoundibular, 2 mm long; pedicel stout, 2 mm long; ovary minutely verrucose, about 1.5 mm long; dorsal sepal elliptical, obtuse, convex above the middle, concave below the middle, 3.25 x 1.75 mm; lateral sepals connate into a suborbicular, concave lamina, obtuse, retuse, 3x3.5mm, bicarinate externally; petals elliptical, upper margin angled, acute, serrulate, yellow with 3 orange veins; lip ovate, fleshy dilated below the middle with the margins turned up. From the latin obscurus, "hidden" or "obscure", referring to the small flowers Type Mexico without locality This species from the eastern declivity of the central highlands of Mexico at elevations around 1200 to 1800 meters as a small sized, cool growing epiphyte is characterized by a rather stout, channeled stem and a thick but narrow, rigid, sulcate leaf about the same length. A small cluster of orange flowers borne on a few abbreviated racemes appears at the base of the leaf. As in some other species, the flowers appear superficially to be in a single flower fascicle. With time the very small fleshy warty flowers turn cinnabar-red. The lateral sepals are united into a semiorbicular retuse lamina, the margins of which evert to expose the thickened lip, while the dorsal sepal reflexes above. The sides of the lavellum below the middle are erect, and centrally there are a pair of rounded lamellae

Synonyms Acianthera obscura (A.Rich. & Galeotti) Pridgeon & M.W.Chase 2001; Humboldtia bilamellata (Rchb.f.) Kuntze 1891; Pleurothallis bilamellata Rchb.f. 1850; Pleurothallis rufa Rolfe 1898

References W3 Tropicos, Kew Monocot list , IPNI ; Refugium Botanicum Reichenbach 1869 as Pleurothallis bilamellata drawing fide; AOS Bulletin Vol 48 No 5 1979; Icones Pleurothallidinarum Systematics of Pleurothallis Vol 3 Luer 1986; An Introdution to the Orchids of Mexico Wiard 1987 photo fide; Lindleyana Vol 16 No 4 2001 as Acianthera obscura; Icones Pleurothallidianrum Vol XXVI Luer 2004 drawing fide; Orchids of Mexico Hagsater, Soto, Salazar, Jimenez Lopez & Dressler 2005 as Acianthera obscura; Guia de Orquideas de Chiapas Carlos Rommel Beutelspacher Baigts 2013 as Acianthera obscura photo fide;

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