AFRICAN

ORCHIDS

Microcoelia obovata Summerh., Bot. Mus. Leafl. 11: 253 (1945).
Description:
Epiphytic plant. Stem up to 30x(2-)3-5 mm, occasionally proliferous. Scale-leaves acute to acuminate, with 5-7 nerves, up to 5 mm long. Roots few to many, variously spreading, loosely to ± densely crowded, often characteristically undulating apically, with a stout ± rigid appearance, mostly loosely attached to the substrate, ± terete, smooth, up to 35(-60) cm x 2—3(—5) mm, in a ± dry state shining in silvery white with darker streaks (small fissures on the surface of the outer velamen layer). Inflorescence(s) ± erect or descending, up to 90(—180) mm long, up to 10 simultaneously, dense to sparse, each with up to 20(—40) flowers; peduncle short, up to 15(—25) mm long; rachis ± straight to indistinctly flexuose, terete to faintly angled, with rows of ± developed verruculae, (fawn colour); bracts mostly sheathing, towards the very apex sometimes progressively not sheathing, acute to subacute, indistinctly 1-nerved, up to 2.5 mm long, (fawn colour) to ± transparent apically. Pedicel distinct, up to 3.2 mm long; ovary slightly curved and furrowed, 1.6-3.2x0.4-0.7 mm, whitish fading into (vinaceous-rufous). Flowers ± horizontal, up to 14 mm long including ovary and pedicel; tepals pure white, at the very base fading into rust-brown (vinaceous-rufous); spur whitish, apex dark-brown; column and anther ± rust-brown. Glandular hairs very sparsely present, in general seen on rachis, base of bracts, pedicel and ovary, more scattered at the base of the tepals. Dorsal sepal slightly convex, obovate to oblong, obtuse, apiculate, with 3 nerves, 3.7-6.Ox 1.2-2.0 mm, at the very apex fading into (vinaceous-rufous) at late anthesis. Lateral sepals slightly asymmetric, oblong, acute, ± apiculate, apically ± reflexed, with 3 nerves, (4.0-)5.2-7.3x(1.2-)l,7-2.3 mm, colour of apex cf. above. Petals ± asymmetric, oblong to obo-vate, apiculate, apically ± reflexed, with 1 sparsely branched mid-nerve, 3.9-6.4x 1.3-1.8 mm. Labellum indistinctly pandurate; mid-lobe broadly obovate, apically ± recurved, ± folded, with 3 nerves, lateral nerves branched; side-lobes indistinct, ± rounded, with a ± rectangular shaped thickening on each side of spur mouth, 4.9—7.6(—9.0) x 3.1—5.1(—5.8) mm\spur slender ± conical, tapering into a ± cylindrical obtuse apex, distinctly incurved, (2.0—)3.3—5.6 mm long, along curve up to 13 mm long, apex (hazel). Column short, truncate, dorsally slightly lobed, (0.4—) 1.1—1.6 mm long, 0.6-2.2 mm high, (vinaceous-rufous) with a central dorsal band fading into (olive lake); androclinium deeply excavated, with a projected deltoidal beak-shaped hump in the centre, its mid-ridge ± pappilose; rostellum- lobes pendant to slightly projected, ± rectangular, up to 0.3 mm long, whitish. Anther hemispherical in side view, with a central groove, tapering into a ± flat, distinctly recurved apex, 0.7-1.2 x 0.8-1.3 mm, (vinaceous-rufous) fading into (olive lake) in the groove. Pollinia asymmetric; in side view kidney-shaped to ± pyriforme, 390-540(-770) x 360-560 µm: in median section oblique, obovate, up to 350 thick, (primrose yellow). Stipes ligulate, spathu-late apically, ± sigmoid, 330-550 µm long, at the apex 80-110 µm wide, transparent; viscidium ± rectangular, rounded distally, 190- 150 x 80-230 pm, transparent. Capsule ± cylindrical, slightly curved, 16-18 x 4-5 mm; pedicel up to 3.5 mm long. Seeds ± fusiform, bottle-shaped to ± cylindrical more rarely, testa cells narrowly elongate (in a dry state), sparsely scattered with variously pointing ± club-shaped processes; anticlinal walls finely furrowed, terminal ends ± elongated, (480-) 570-660(-700) x 70-90 µm. Scent not percepted.
Habitat:
Woodland to wooded grassland or in dry riverine forest. Epiphytic in more or less exposed conditions, often found high up in tree crowns. Altitude. 400-1100 m.
Flowering period:
Mainly in the beginning and the end of the early rainy season.
Cultivation:
As given for the genus, hot to warm growing epiphyte.
Distribution:
Kenya to NE. KwaZulu-Natal
References:
Orchids of East Africa Piers 1968; AOS Bulletin Vol 48 No 2 1979; A Monograph of the Genus Microcoelia [Orchidaceae] Jonsson 1981; Flora of Tropical East Africa Orchidaceae Part 3 Cribb 1989; Orchids of Kenya Stewart 1996; African Orchids in the Wild and Cultivation LaCroix 1997; Flora Zambesiaca Vol 11 Part 2 Pope 1998; Angraecoid Orchids Stewart, Hermans and Campbell 2006; WCSP (2017). 'World Checklist of Selected Plant Families. 03.03-2017; http://apps.kew.org/wcsp/
Images:
Click on each image to see a larger version.

Habitat/In situ Habitat/In situ
microcoelia obovata Microcoelia obovata02
Photograph©Backmann. Swiss Orchid Foundation at the Herbarium Jany Renz Image used with kind permission. Photograph© Lourens Grobler. Image used with kind permission.