AFRICAN

ORCHIDS

Polystachya coriscensis Rchb.f., Otia Bot. Hamburg.: 112 (1881).
Homotypic Synonyms:
Dendrorkis coriscensis (Rchb.f.) Kuntze, Revis. Gen. Pl. 2: 658 (1891).
Heterotypic Synonyms:
Polystachya bituberculata Kraenzl., Bot. Jahrb. Syst. 28: 165 (1900).
Polystachya kiessleri Schltr., Bot. Jahrb. Syst. 38: 153 (1906).
Description:
Plant up to 20 cm tall. Pseudobulbs 1.5-2.5 cm long, 0.5 cm in diameter, conical, covered at base by few sheaths and with 2-5 leaves above. Leaves 3-8(15) cm long, 0.4-2.5 cm wide, oblanceolate, oblong-elliptic to elliptic, very obscurely bilobed at obtuse apex. Inflorescence 4.5-12 cm long, densely 10-25-flowered, branching, covered at base by 2-3 imbricating sheaths; rachis pubescent. Flowers small, greenish-white or yellow with brown or rose- coloured stripes, pleasantly smell. Floral bracts 2-6 mm long, setaceous, minutely pubescent. Pedicel and ovary 1-2.8 mm long slender, densely pubescent. Dorsal sepal 2.6-4 mm long, 1.3 mm wide, ovate-triangular, long-apiculate, thin, delicate, more or less pubescent on the outer surface, 3-nerved. Lateral sepals 5-6 mm long, 3-6 mm wide, obliquely triangular or triangular-ovate, long-apiculate, concave, thin, more or less pubescent on the outer surface, 3-nerved. Mentum 3-5 mm long, saccate. Petals 2.1-3 mm long, 0.3-0.4 mm wide, oblong-lanceolate to linear, acute or acuminate, thin, glabrous, 1-nerved. Lip 3.4-5.2 mm long, 2.5-3.5 mm wide, distinctly 3-lobed in the middle or in the apical third, thin, delicate, without any callus, basal part obtriangular to half-rotundate; lateral lobes 0.8-1.1 mm wide, triangular-ovate, rounded, sparsely ciliate on the inner surface; middle lobe 1.1-2.7 mm long, 0.8-1.9 mm wide, oblong-ovate, apiculate.
Habitat:
An epiphytic herb growing in moss on branches of trees in evergreen forest. Altitude sea level to 690 m.
Cultivation:
This is an attractive species with flowers that are larger than is usual in this section and pleasant foliage. The leaves, however, seem prone to developing black streaking, which suggests that plants need careful watering and good air circulation. Flowers in autumn and early winter (November and December).
Notes:
Polystachya coriscensis is related to Polystachya parviflora, but its lip lacks any callus and is distinctly 3-lobed (not rhombic in outline).
Distribution:
SW. Ivory Coast, Nigeria to WC. Trop. Africa
References:
African Orchids in the Wild and Cultivation La Croix 1997; Orchidaceae of West Central Africa Vol. 2 Szlachetko etal 2015; A Monograph of the subtribe Polystachyinae Schltr. (Orchidaceae) by Joanna Mytnik-Ejsmont, University of Gdansk 2011; World Checklist of Monocotyledons. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/monocots/ accessed 05.04.2017
Images:
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