AFRICAN

ORCHIDS

Microcoelia corallina Summerh., Bot. Mus. Leafl. 11: 250 (1945).
Description:
Epiphytic plant. Stem short, 4-10 x 1.5-3 mm. Scale-leaves acute to acuminate, with c. 3 nerves, up to 2.5 mm long. Roots many, ± radially spreading, densely crowded, sligh tly undulating, unbranched, mostly characteristically attached to the substrate forming a ± conical tuft, terete to slightly flattened, smooth, up to 90 x 1.5-3 mm. Inflorescence(s) short, ± erect, spreading, up to 10-25 mm long, up to 3(-6) simultaneously, usually dense, each with up to15 flowers, ± concentrated at the apex of rachis; peduncle indistinct; rachis straight, terete, ± excavated at the bracts, aciculated, swollen below the bracts; bracts only sheathing at the very base, all the rest not sheathing, acute to acuminate, 1-nerved, 1.0-1.8 mm long. Pedicel long, ± straight, furrowed, up to 2.3-3.9 mm long; ovary slightly curved, furrowed, valves obtusely keeled, 1.6-2.3 x 0.7 mm, whitish tinged with coral pink. Flowers ± erect-spreading, up to 6 mm long including ovary and pedicel; tepals pure white with a coral pink central line, the swellings at the base of labellum, apex of spur, anther and column all coral pink. Tepals dissimilar, provided with large crystal sacks (idioblasts), more densely near the central nerve. Glandular hairs sparse, mainly scattered on rachis, base of bracts, pedicel and ovary, basal part of the perianth to the apex of the spur. Dorsal sepal elliptic, subacute, slightly convex, with 1 nerve, apically ± recurved, 2.3-2.9 x. 1-1.4 mm. Lateral sepals asymmetric, ovate, ± apiculate, 1-nerved, lower side-lobe rounded, 2.4-3.2 x 1.3-1.7 mm. Petals elliptic to oblong, subtruncate, 1-nerved, 2.1-2.7 x 1.0-1.4 mm. Labellum ± orbicular in outline, slightly folded, ± notched, with a ± distinct elongated thickening at each side of spur mouth, with 3 nerves, lateral nerves sparsely branched, 2.5-2.8 x 2.3-2.4 mm; spur ± straight, slightly apressed to the ovary or ± de pendent, towards the base narrowly cylindric, apical inflation rhombic to narrowly elliptic in outline, subacute, 3.0-5.2 mm long, 0.5-1.1 mm at the widest part. Column short, truncate, dor-sally ± vaulted, laterally ± incumbent, 0.5-0.8 mm long and 0.4-0.9 mm high; androclinium shallowly excavated, with a distinct narrow mid-ridge; rostellum lobes short, obtuse, ± deltoid, up to 0.2 mm long. Anther semiobovate in side view, slightly flattened frontally, ± truncate, obtusely apiculate, 0.7-0.8x0.6-0.9 mm. Pollinia ± asymmetric; in side view elliptic to obovate, 310-450x310-340 µm;, in median section ± elliptic, up to 270 µm thick. Stipes ligulate, slightly spathulate apically, ± sigmoid, 270-380 µm long, 80-110 pm wide at the apex; viscidium oblong to broadly transversely elliptic, obtuse, ± notched at the posterior end, membranous, 230-280 x 230-270 µm.
Habitat:
Hot, dry open woodland, usually near a river, growing most often on smooth-barked trees such as baobab, which are avoided by most orchids. Altitude. 460-670 m.
Flowering period:
During the transition to the early rainy season.
Cultivation:
As given for the genus, hot growing epiphyte.
Distribution:
Tanzania to Mozambique
References:
A Monograph of the Genus Microcoelia [Orchidaceae] Jonsson 1981; Orchids of Kenya Stewart Campbell 1996; African Orchids in the Wild and Cultivation La Croix 1997; Flora Zambesiaca Vol 11 Part 2 Pope 1998; Angraecoid Orchids Stewart, Hermans and Campbell 2007; WCSP (2017). 'World Checklist of Selected Plant Families. 03.03-2017; http://apps.kew.org/wcsp/
Images:
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Photograph© Lourens Grobler. Image used with kind permission. Photograph© Lourens Grobler. Image used with kind permission. Photograph© Lourens Grobler. Image used with kind permission. Photograph© Lourens Grobler. Image used with kind permission. Photograph© Lourens Grobler. Image used with kind permission. Photograph© Lourens Grobler. Image used with kind permission. Photograph© Lourens Grobler. Image used with kind permission.