AFRICAN

ORCHIDS

Disperis thomensis Summerh., Bull. Misc. Inform. Kew 1937: 458 (1937).
Description:
Terrestrial herb 9–15 cm tall; tuber c. 1 cm long ± cylindrical, woolly. Leaves 2, opposite, dark green, shortly petiolate, sheathing at the base, 2–5 × 1.3–3.5 cm, ovate, shortly acuminate, the margins undulate. Inflorescence 1–4-flowered; flowers white marked with green and purple, held horizontally. Ovary 12–17 mm long; bracts leaf-like, of similar length. Dorsal sepal lanceolate, acute, concave, bent above the middle, joined to petals to form a hood c. 5 mm long. Lateral sepals free, 5–6 × 2.5–3 mm, obliquely obovate, aristate at the apex, with incurved, conical spur 2–2.5 mm long near inner edge. Petals 5.3–6.5 mm long, narrowly oblong, the front edge with a rounded lobe at base, the posterior edge with a suberect median lobe 1.5 mm long; apex shortly bifurcate, the anterior fork longer than the posterior. Lip 4.5–7 mm long, the apex bent abruptly inwards and shortly apiculate, the front face joined to the apex of 2 papillose appendages; appendages 6 mm long, 2-lobed with one lobe straight, the other recurved.
Habitat:
In leaf litter in evergreen and riverine forests from 1300 to 2150 m, sometimes also as a low-level epiphyte. 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.
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.