Habenaria cornuta Lindl., Companion Bot. Mag. 2: 208 (1837).
Homotypic Synonyms:
Ceratopetalorchis cornuta (Lindl.) Szlach., Górniak & Tukallo, Richardiana 3: 161 (2003).
Heterotypic Synonyms:
Habenaria ceratopetala A.Rich., Ann. Sci. Nat., Bot., II, 14: 267 (1840).
Habenaria ruwenzoriensis Rendle, J. Bot. 33: 280 (1895).
Habenaria orthocaulis Schltr., Bot. Jahrb. Syst. 53: 519 (1915).
Habenaria subcornuta Schltr., Bot. Jahrb. Syst. 53: 510 (1915).
Bilabrella orthocaulis (Schltr.) Szlach. & Kras, Richardiana 6: 197 (2006).
Description:
A terrestrial herb 2-8 dm. high, glabrous except for the roots. Tubers ellipsoid, elongate-ovoid or nearly globose, 1.5-3.5 cm. long, 1-2 cm. in diameter, densely tomentose. Stem erect, slender to rather stout, leafy throughout its length. Leaves 9-15, the lowermost 1 or 2 reduced to sheaths, the middle 4-6 ± spreading or recurved, linear-lanceolate to ovate, acute, the largest 2-10 cm. long and 0.7-4.5 cm. broad, the upper ones smaller, adpressed to the stem, lanceolate, decreasing in size upwards, similar to the bracts. Inflorescence 5-19 cm. long, 3-6 cm. in diameter, loosely to densely 4- to many-flowered. Bracts leafy, lanceolate, acute, 1-2.7 cm. long, mostly shorter than the pedicel with ovary. Flowers suberect, pale green or yellow-green; pedicel with ovary almost straight, 1.8-2.8 cm. long. Dorsal sepal erect, very convex and almost boat-shaped, subacute, 5-16 mm. long, 4-8 mm. broad when flattened out; laterals deflexed, obliquely semi-orbicular, ± rolled up lengthwise, acute, 6-16 mm. long, 5.5-10.5 mm. broad. Petals bipartite nearly to the base; posterior (upper) lobe ± erect, usually adherent to the dorsal sepal, linear, 6.5-14.5 mm. long, ± 0.5 mm. broad; anterior lobe curling upwards like a long horn, linear below, subulate above, 2.4.5 cm. long, 1-2 mm. broad. Lip deflexed, tripartite from an undivided basal part ± 1 mm. long; middle lobe ± incurved in the apical part, linear, obtuse, 9.5-19 mm. long, ± 1 mm. broad; side lobes somewhat diverging, narrowly lanceolate or lanceolate-linear from a broad base, tapering in the apical part, often with I or 2 short teeth or shortly pectinate on the outer margin at about the middle, 8-18 mm. long, 1-2.5 mm. broad towards the base; spur dependent, much swollen in the apical half or third, 1.4-2.7 cm. long. Anther erect, 3-7.5 mm. high, canals porrect or ± incurved, rather slender, 4.5-8.5 mm. long; stigmas porrect, widened at the truncate apex, 3-8 mm. long, rostellum triangular, acute, ± 1 mm. long.
Habitat:
Brachystegia woodlands, montane often badly drained grasslands, marshy ground, dambos. Alt. 850-2400 m.
Phenology:
Flowering in May-September.
Notes:
This species exhibits a great range in variation in the shape of the leaves, the density and number of flowers in the inflorescence, the size of the flowers and the side lobes of the lip. The first two types of variation are common to the whole range of the species. As regards size the flowers tend to be smaller in the extreme north, west and south of the range while larger-flowered plants occur mostly in the centre of the range, particularly in Tanganyika, Malawi and Rhodesia. This is also true of the lateral lobes of the lip which are entire in South Africa and in the extreme north, but are often variously toothed in the intermediate regions.
The species is also very much subject to the production of abnormal plants in which the flowers, particularly the lateral petals, are not properly developed. Several such plants have been made the basis of distinct species, e.g. Habenaria ruwenzoriensis Rendle and Habenaria orthocaulis Schltr. Usually the normally long horn-like anterior petal-lobe is short and stumpy while the posterior lobe may be more or less antheriferous. Plants have been seen in which some flowers are perfect whereas others are more or less abnormal.
Cultivation:
As given for the genus.
Distribution:
Nigeria, Cameroon, Central African Republic, the Republic of Congo, the Democratic Republic of Congo (Zaire), Ethiopia, Uganda, Kenya, Tanzania, Zambia, Malawi, Zimbabwe, South Africa.
References:
Orchidaceae of West-central Africa, vol. 1, Gdansk University Press Gdansk 2010, La Croix, I. et al. (1991). Orchids of Malawi A.A. Balkema, Rotterdam; La Croix, I. & Cribb, P.J. (1995). Orchidaceae (Part 1) Flora Zambesiaca 11(1); Flora of Tropical East Africa Summerhayes Orchidaceae Part 1 1968; CONTRIBUTION À L'ÉTUDE DES ORCHIDACEAE DU BURUNDI (DEUXIÈME PARTIE) D. GEERINCK, Belgian Journal of Botany, Vol. 129, Fasc. 1 (1996), pp. 66-70: African Orchids: X V. S. Summerhayes, Bulletin of Miscellaneous Information (Royal Botanic Gardens, Kew), Vol. 1938, No. 4 (1938), pp. 141-153
Images:
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Habitat/In situ	Habitat/In situ	Habitat/In situ	Habitat/In situ
Photograph© Nicholas Case Wightman Image used with kind permission.	Photograph© Nicholas Case Wightman Image used with kind permission.	Photograph© Nicholas Case Wightman Image used with kind permission.	Photograph© Nicholas Case Wightman Image used with kind permission.