Bonatea stereophylla (Kraenzl.) Summerh., Kew Bull. 4: 430 (1949).
Habenaria stereophylla Kraenzl., Orchid. Gen. Sp. 1: 959 (1901).
Habenaria polychlamys Schltr., Bot. Jahrb. Syst. 53: 508 (1915).
Erect, decumbent or scandent terrestrial herbs, 500-700 mm tall; tubers 2, spreading, elongate-oblong, tomentose. Stem robust, 490-695 x 8-10 mm. Leaves withered at flowering, 15-20, dense, lower sheathing, oblong, acute, 50-60 mm broad. Inflorescence cylindrical, 150 x 80 mm, dense, 10-20-flowered; bracts sometimes withered at flowering, lanceolate to ovate-lanceolate, acuminate, 30-40 mm long. Flowers spreading, greenish yellow, pedicel and ovary sub-erect, 30-35 mm long. Dorsal sepal green, erect, elliptical-lanceolate, galeate, acuminate, 20-25 x 8-10 mm; lateral sepals green, patent, decurved, narrowly-triangular, acuminate to apiculate, base oblique, 20 x 4 mm, adnate to lip and stigmatic processes for 3-4 mm. Petal upper lobe erect, linear, acute to acuminate, 18-20 x 1.5-2.0 mm, adnate to dorsal sepal, lower lobe weakly falcate, linear, acuminate, 17-27 x 1 mm, adnate to claw of lip for 2-3 mm. Lip claw 4.5-6.0 mm, median lobe descending, straight, linear, acute to acuminate, 15-21 x 1 mm, lateral lobes descending, linear, tips curved, apiculate, 21-25 x 1 mm; spur toothed, curved, 28-35 mm long, clavate apex 18-25 mm long. Anther erect, acute, 12 mm long, canals slender, 8-10 mm long. Stigmatic processes clavate, projecting forwards and sometimes deflexed, 15-16 mm long, base adnate to lip. Rostellum 3-lobed, base auriculate, median lobe elongate-rostrate, acute, margin smooth, 8-11 mm long, lateral lobes linear, fused to anther canals, sub-erect to 45°, sub-parallel or slightly divergent, 4-6 mm long. Flowering period: April.
Grassland, to approximately 2100 m altitude.
Bonatea stereophylla is a rare species, known from only two collections. This deciduous species has a large distinctive tooth (> 5 mm long) in the spur mouth, an elongate-rostrate rostellum mid-lobe, straight labellum mid-lobe, narrowly triangular lateral sepals, and flowers described as yellowy green (Schlechter, 1915). Morphology suggests the closest allies are B. polypodantha (Rchb.f.) L.Bolus and B. pulchella Summerh.
SW. Tanzania (Ukinga Mts.)