Habenaria rautaneniana Kraenzl., Bull. Herb. Boissier, II, 2: 941 (1902).
Homotypic Synonyms:

Mirandorchis rautaneniana (Kraenzl.) Szlach. & Kras-Lap., Orchidee (Hamburg) 54: 85 (2003).
Description:

Terrestrial herb to 80 cm tall; tubers to 3.5 × 2 cm, ovoid or ellipsoid, tomentose. Stem leafy. Leaves 5–11, the largest erect, 18–33 × 0.5–1.5 cm, linear-lanceolate, conduplicate, sheathing at base. Inflorescence to 24 × 7 cm, fairly densely many-flowered; bracts 1.5–3.5 cm long. Flowers yellow-green, the side lobes of lip white at base. Ovary and pedicel 5 cm long. Dorsal sepal erect, 9.5–15 × 3.5–5 mm, elliptic, obtuse, convex; lateral sepals spreading, 11–18 × 6–8.5 mm, obliquely ovate, acuminate. Petals 2-lobed almost to base; upper lobe 9–15 mm long, narrowly linear, adnate to dorsal sepal; lower lobe 14–23 × 0.5–1.5 mm, linear, spreading upwards. Lip 3-lobed to 2–3 mm from base; mid-lobe 11.5–20 × 1–1.5 mm, linear, somewhat deflexed; side lobes spreading, 11–17 × 1.5–3 mm, lanceolate-ligulate, subacute, the apices slightly upturned, densely pubescent or papillose at base; spur 14–23 mm long, recurved with 1 twist in middle, swollen to c. 2 mm diameter in apical half. Anther erect, 6.5–9.5 mm tall, canals c. 2 mm long, partly adnate to column, upcurved at tips. Stigmatic arms 5.5–7.5 mm long, club-shaped, curving down over base of lip. Rostellum mid-lobe 2.5–4 mm long, narrowly triangular, acute.
Habitat:

Marshy ground, dambos or seasonally flooded grassland, often growing in slowly running water c. 1100–1150 m.
Distribution:

Ethiopia to Namibia

Images:
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Botanical Drawing / Herbarium

Photograph copyright Swiss Orchid Foundation at the Herbarium Jany Renz Image used with kind permission.