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Disperis thomensis Summerh., Bull. Misc. Inform. Kew 1937: 458 (1937).
Description:
Tuber ca. 1 cm long, cylindrical, woolly. Stem 8.5-17 cm tall, erect, glabrous. Leaves 2, opposite, above the middle of the stem, shortly petiolate; petiole up to 0.7 cm long, sheating at the base; blade 2-5 cm long, 1.1-3.5 cm wide, ovate to ovate-lanceolate, acute to shortly acuminate, slightly cordate to truncate at the base, undulate along margins. Inflorescence 1-4-flowered. Flowers white, marked with green and purple, held horizontally. Floral bract 3-17 mm long, ovate with lanceolate apex. Ovary up to 17 mm long, erect, slender. Hood up to 6 mm deep, 4-dentate at the apex, spur cylindrical, distinctly swollen in the apical half, rounded. Dorsal sepal up to 12.5 mm long and 1.7 mm wide, linear-lanceolate, acute. Petals slightly longer, up to 3 mm wide, 3-lobed, all lobes triangular, acute, the apical one the smallest, the middle one close to the apical one, the basal lobe distinctly remote from both other. Lateral sepals 5-6 mm long, 2.5-4 mm wide, obliquely ovate, aristate at the apex, with incurved, conical, subacute spur, 2-2.5 mm long. Lip set on a long, linear claw up to 7 mm long, reflexed abruptly at the apex; limb up to 2 mm long, linear, subacute, densely papillate; appendages 4-6 mm long, 2 mm across the apex, bi-lobed, lobes linear, obtuse, divergent, papillate.
Habitat:
In leaf litter in evergreen and riverine forests from 1300 to 2150 m, sometimes also as a low-level epiphyte.
Phenology:
Flowering mainly between January and April in south-central and eastern Africa, and from August to November in West Africa.
Notes:
Clearly related to the East African Disperis kerstenii Rchb. f., on the one hand, and to Disperis dicerochila Summerhayes on the other. In the former the appendages of the lip are much longer, are free from the base and the apical lobes are somewhat spreading or retrorse. In Disperis dicerochila the appendages, although free as in Disperis kerstenii, are even shorter than in Disperis thomensis. In neither species are the appendages reflexed halfway along; in Disperis kerstenii they are reflexed with respect to the lip from their point of origin, while in Disperis dicerochila they are erect.
Cultivation:
As given for the genus.
Distribution:
Widespread in tropical Africa from Zambia and Angola northwards to Kenya in the east and Guinea in the west, also known from islands off the West African coast such as São Thomé and Bioko.
References:
Orchidaceae of West-central Africa, vol. 1, Gdansk University Press Gdansk 2010; A synopsis of the genus Disperis Sw. (Orchidaceae), ADANSONIA, sér. 3 - 2005 - 27 (2) : 155-207
Images:
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Habitat/In situ	Habitat/In situ	Habitat/In situ
Photograph© João Farminhão/ Missouri Botanical Garden. Image used with kind permission.	Photograph© João Farminhão/ Missouri Botanical Garden. Image used with kind permission.	Photograph© João Farminhão/ Missouri Botanical Garden. Image used with kind permission.