AFRICAN

ORCHIDS

Microcoelia leptostele (Summerh.) L.Jonss., Symb. Bot. Upsal. 23: 127 (1981).
Homotypic Synonyms:
Encheiridion leptostele Summerh., Kew Bull. 8: 588 (1953 publ. 1954).
Description:
Epiphytic plant. Stem ± stout, terete, up to 40 x 4-5 mm. Scale-leaves acuminate to rostrate, with 7-11 nerves, up to 7.4 mm long. Roots many, thick, variously twining, forming a ± dense mass around the stem, few branched at distal ends, ± terete, smooth, up to c. 30 cm x 2.0-3.0 (-5.0) mm (most of the existing material has pruned roots). Inflorescence(s) ± erect, spreading, up to 4 (-5.5) cm long, up to 10 (-20) simultaneously, usually ± dense, each with up to 5-10 flowers; peduncle short, up to 5 (-lO)mrn long; rachis indistinctly flexuose, ± smooth; bracts sheathing, acute to subacute, basal 3-nerved, apical indistinctly 1-nerved, up to 2.3 mm long. Pedicel distinct, straight or twisted, up to 2.0 mm long; ovary ± straight, slightly furrowed, up to 2.0 mm long, 0.7 mm in diameter. Flowers ± horizontal, up to 12 mm long including ovary and pedicel; perianth whitish-yellow. Glandular hairs sparse, in furrows of the ovary, base of perianth and spur. Dorsal sepal distinctly hood-shaped, ± elliptic, acuminate or subacute, apex ± recurved, 5-nerved, 8.0-8.5x4.0-6.5 mm. Lateral sepals slightly asymmetric, ± convexed to slightly folded, oblong, acuminate, subapiculate, 3-nerved, lateral nerves branched or not, 7.5-8.8 x 2.9-3.1 mm. Petals indistinctly asymmetric, convex, elliptic, acute, ± apiculate, 3-nerved, lateral nerves branched or not, 5.3-7.5 x 2.8-3.3 mm. Labellum 3-lobed; mid-lobe shortly spathulate, parabolic, apiculate to tridentate, ± erose, ± cup-shaped and folded in natural position, 5-nerved, lateral nerved branched; with a distinct hump-shaped thickening at the front of spur mouth; side-lobes raised, rounded, margin distinctly thickened, 6.7-9.1 x 3.4-5.0 mm, midlobe alone 4.1-7.0 mm. Spur long, ± flattened dorsiventrally, incurved; apical inflation distinct, with ± flattened facets, ± circular to ± obtriangular in outline, 6.5-8.1 mm long (along curve up to 13 mm long), apical inflation up to 2.0 mm in diameter in side view. Column long, ± erect, slender, ± curved, tapering apically, 4.2-5.4 mm long, 1.0-1.4 mm high; androclinium shallowly excavated, ± vertically orientated; rostellum-lobes very long, acute, inserted on the lower 1/3 of the column, bifid from the base, ± porrect in anthesis, in early anthesis pointing into spur mouth, 6.0-7.2 mm long, at the base each lobe is up to 0.5 mm wide. Anther hemispherical in side view, at the base bivalvate, frontally ± flattened, tapering into an inflexed, long and obtuse apex, ± recurved, 3.0-4.0(-4.5) x 1.6-2.5 mm. Pollinia asymmetric; in side view ± orbicular, 800-900 x700-800 µm; in median section obovate, up to 650 µm thick. Stipes long, ligulate, sigmoid; apical free part with an obconical head-like apex, ± channeled, at the base flattened, 4.8-6.5 mm long; basal part connate to the apex of the viscidium, ± grooved; viscidium narrowly elliptic, apex rounded, base truncate, notched or not, 5.1-5.5x0.65-0.78 mm. Capsule ellipsoid to narrowly ellipsoid, ± curved, smooth, indistinctly ribbed, 25-27 mm long, 3.5-6.0 mm in diameter; pedicel short, up to 7 mm long. Seeds ± cylindrical, bottle-shaped to fusiform, testa cells narrowly elongate (in a dry state), with ± club-shaped and distinctly hook-shaped processes; anticlinal walls sulcate with few to many finer striations, terminal ends slightly protruding, (290-)350-450(-510) x 50-70 µm (25 dry seeds measured).
Habitat:
Epiphyte, in rain forest and in secondary vegetation near rivers, usually in the crowns of understorey trees; 200-1000 m; flowering in March.
Flowering period:
Early rainy season.
Cultivation:
As given for the genus.
Distribution:
WC. Trop. Africa
References:
WCSP (2017). 'World Checklist of Selected Plant Families. 03.03-2017; http://apps.kew.org/wcsp/
Images:
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