Orchidaceae (Part 1) part.
Creators: name: Summerhayes, V. B.
Publisher: name: Zenodo
Year: 1968
Subjects: Biodiversity
Taxonomy

description: 17. DISPERIS *
Sw. in Yet. Acad. Handl, Stockholm, ser. 2, 21: 218 (1800); Schltr. in Bull. Herb. Boiss. 6: 911(1898)
Erect mostly small terrestrial herbs arising from small tubers and in the Flora area usually growing in very shallow soil or leaf-mould in forest. Stems with 1-several sheathing scale-leaves (cataphylls) at the base. Leaves 1-few, alternate or opposite, rarely almost obsolete. Flowers small, mostly under 2*5 cm. long, white, yellow, green, pink or magenta, solitary or in severalmany-flowered racemes; bracts leaf-like. Dorsal (intermediate) sepal united with the petals to form a structure which varies from an almost flat limb to an elongate spur; lateral sepals each with a conspicuous spur or pouch near the inner margin (lacking in one South African species). Petals variously shaped, often falcate, obliquely acute or lobed at the apex, sometimes auriculate at the base. Lip remarkably modified, its claw joined to the face of the column and ascending above it, variously curving into the spur if present, often dilated into a smooth or papillate, straight or reflexed limb and usually bearing a simple or 2-lobed appendage which varies greatly in shape from species to species. Column erect, mostly stout; rostellum large, membranous, 2-lobed, produced in front into 2 rigid cartilaginous arms (fitting into the lateral sepal-pouches when in bud) holding the glands of the pollinia at their apices; anther-bearing part of column horizontal or ascending; anther-loduli distinct, parallel, ± approximate; pollinia-granules secund in a double row on the margins of the flattened caudicles which curl up in a spiral on removal; staminodes present in some species; stigma 2-lobed, the lobes situated on either side of the adnate claw of the lip. Capsule cylindrical or ovoid, ribbed.
* By B. Verdcourt.
A genua of ± 75 species extending from Togo and Ethiopia through tropical Africa to South Africa, the Mascarene Is., India and thence to New Guinea.
Schlechter divides the genus into two sections, Disperis sensu stricto (Eudisperis Schltr.) and Anaphyllum, Schltr., the former with clearly alternate leaves and the latter with opposite or practically opposite leaves.
Nearly half the species are South African but it is likely that too many have been described in certain groups. It has been suggested that the basal appendages on the lip in species 1-5 (and possibly even 6) are not homologous with the true apical appendages found in other species. Summerhayes (Hook., Ic. PI. 33, t. 3270 (1935)) suggests they are due to a splitting of the actual lip-claw. In this group the true appendage may well be represented by the papillate crest on the limb which is visible in some of them. In this account the word appendage has its simple dictionary meaning. The species are readily identified by careful examination of the lip but since the shapes are not easy to describe the key has been supplemented by a plate (fig. 39, p. 220) showing the lips, the species being numbered as in the account that follows.
Intermediate sepal fused with petals to form an open or boat-shaped structure (hood) but never a distinct spur:
Leaves alternate or stems 1-foliate or if lowest pair subopposite then upper 1-2 distant:
Plant glabrous; limb of lip (or upper appendage) conic-ellipsoid or an ovate to rounded lamina bearing a papillate crest; basal lip-appendage papillate, situated just above junction of claw of lip with the column:
Hood deeply concave, as broad as long even when not opened out flat; basal appendage of lip typically a papillate reniform blade, emarginate at the tip but sometimes deeply 2-lobed... 1. D. katangensis
Hood smaller and flatter, longer than broad; basal appendage deeply 2-lobed:
Limb of lip flat, bearing a papillate crest or spur:
Petals not half-cordate, the hood rounded or narrowed at the base. 2. D. johnstonii
Petals half-cordate, the hood distinctly cordate at the base... 3. D. togoensis
Limb of lip (upper appendage) fleshy, oblong-cuneate or hoof-shaped, mostly joined to the claw by the middle..... 4. D. reichenbachiana
17. Disperis
Stem and ovary hairy; claw of lip strongly reflexed and ending in a papillate triangular appendage produced at its apex into a linear tip; leaf and bract ciliate; a small plant only ± 3-5 cm. tall.. 6 D. pusilla
Leaves opposite:
Lip with 2-lobed papillate appendage near the junction of the claw with the column; limb reflexed, linear.. 5. D. leucomura
Lip with apical structure consisting of a short reflexed linear limb and 2 much longer glabrous appendage-lobes each of which is itself 2-lobed .... 7 D. dicerochila intermediate sepal and petals joined to form a distinctly spur-like structure:
Lip with long linear claw, 105 mm. long, ending in an entire papillate carrot-shaped appendage; lateral sepals almost entirely joined. D. gregia
Lip with appendage divided or if not then of a totally different shape; lateral sepals not joined for more than half their length:
Leaves alternate or absent (the basal scale leaves are always present):
Lip-appendage not divided:
Lip with terminal triangular limb bearing an oblong appendage where the limb is bent; leaves well developed, 1-3 cm. long..... 9. D. kilimanjarica
Lip with short narrow reflexed limb beyond which protrudes a narrow linear appendage dilated at the apex and somewhat resembling the condyle of a bone; leaves reduced, 2-9 mm. long.0 10. D. parvifolia
Lip-appendage deeply divided into 2 narrow lobes much longer than the short limb. 12. D. aphylla subsp. aphylla
Leaves opposite or almost so:
Spur relatively short and broad or curved; lip-appendage deeply 2-lobed:
Appendage-lobes with an apical deflexed tooth 3 mm. long....11. D. kerstenii
Appendage-lobes without an apical tooth but ± lobulate near their base.. 12. D. aphylla subsp. bifolia
Spur narrow, straight and tube-like, 0-9- 2 cm. long; lip-appendage almost obsolete or not deeply 2-lobed:
Lip reaching end of spur where it is recurved and terminates in a long flattened linear-oblanceolate appendage 9 mm. long, nearly reaching mouth of the spur....13 D. nemorosa
Lip not reaching end of spur; appendage and limb reduced to vestiges, the former fimbriate and the latter linear, together only 1-5 mm. long. 14 D. anthoceros
description: Published as part of Summerhayes, V. B., 1968, Orchidaceae (Part 1) part. in Flora of Tropical East Africa 1 (1) on pages 216-218