Bonatea volkensiana (Kraenzl.) Rolfe in D.Oliver & auct. suc. (eds.), Fl. Trop. Afr. 7: 253 (1898).
Habenaria volkensiana Kraenzl., Bot. Jahrb. Syst. 19: 244 (1894).
Erect, decumbent or scandent terrestrial herbs, 210-660 mm tall; tubers 2-10, spreading, elongate-oblong, tomentose. Stem slender to robust, 205-650 x 2.5-10.5 mm. Leaves 7-15, lax to dense, cauline, lower sheathing, blades reduced, lanceolate to oblanceolate, acute to acuminate, margins entire, smooth to undulate, 27-123 x 10-41 mm. Inflorescence cylindrical, 89-221 x 55-123 mm, lax to dense, 6-27flowered; bracts similar to upper leaves, sheathing, lanceolate to ovatelanceolate, apiculate, 16-35 x 5-12 mm. Flowers spreading, green and white, pedicel and ovary sub-erect to erect, 25-43 mm long. Dorsal sepal green, erect, elliptical-lanceolate, galeate, acute to acuminate, 13.0-18.5 x 4-8 mm; lateral sepals green, patent, strongly deflexed, widely oblong-ovate, acute to apiculate, base oblique, margins weakly revolute with acute tooth on lower margin, 11.5-17.5 x 5.5-9.5 mm, adnate to lip and stigmatic processes for 4.5-8.0 mm. Petals upper lobe green, erect, linear, acute to acuminate, 12.5-19.5 x 0.5-2.0 mm, adnate to dorsal sepal, lower lobe white with green tip, projecting forwards, ascending, weakly divergent, linear-falcate, tip curved, acuminate, (21-)25-38.5 x 0.5-1.5 mm, adnate to claw of lip for 3-6 mm. Lip claw 10.0-14.5 mm, median lobe green, descending, geniculate, sometimes apically recurved, linear-lanceolate to narrowlyoblong, acute to acuminate, 11.5-25.0 x 1.0-2.5 mm, lateral lobes white with green tips, projecting forward, ascending, diverging, linearfalcate, tips curved, acuminate, (16.5-)20-32.0 x 0.5-1.5 mm; spur toothed, 23-36 mm long, clavate apex 8.0-16.5 mm long. Anther erect, acute, 5-8 mm long, canals slender, 9.0-14.5 mm long. Stigmatic processes clavate to spathulate, projecting forwards and deflexed, sub-parallel, 11.5-18.0 mm long, base adnate to lip. Rostellum 3-lobed, base auriculate, median lobe cucullate, acute to acuminate, margin ciliate, 3.0-5.5 mm long, lateral lobes linear, fused to anther canals, sub-erect to 45°, sub-parallel, 4.5-7.0 mm long. Flowering period: rarely January to February, March to June.
Grassland and savannah, 1000-2200 m altitude.
Bonatea volkensiana is distributed inland and is allopatric with coastal populations of B. rabaiensis. This species has a similar posture of the elongate rostellum side lobes (ascending >45°) to B. steudneri and B. lamprophylla, but the morphology and posture of its lower petal lobes and labellum closely resemble Bonatea antennifera Rolfe.
SW. Kenya to N. Tanzania