AFRICAN

ORCHIDS

Microcoelia koehleri (Schltr.) Summerh., Bot. Mus. Leafl. 11: 158 (1943).
Homotypic Synonyms:
Angraecum koehleri Schltr., Bot. Jahrb. Syst. 38: 162 (1906).
Gussonea koehleri (Schltr.) Schltr., Beih. Bot. Centralbl. 36(2): 93 (1918).
Heterotypic Synonyms:
Gussonea friesii Schltr. in R.E.Fries, Wiss. Erg. Schwed. Rhod.-Kongo Exped. 1: 250 (1916).
Microcoelia friesii (Schltr.) Summerh., Orchid Rev. 47: 21 (1939).
Microcoelia pachystemma Summerh., Orchid Rev. 47: 21 (1939).
Description:
Stem up to 40 x 2.0-3.0 (-5.0) mm. Scale-leaves acute to acuminate, with about 5 nerves, up to 4.0 mm long. Roots many, variously spreading, rarely with few branches distally, often forming dense ± conical-shaped tufts, ± closely attached to the substrate, constrictions after last growth are often present, ± undulating, terete to slightly flattened where adnate to the substrate, smooth, up to 20 cm x 1.0—2.0 (-3.0) mm, when living having a dull greyish-green lustre in a ± dry state, lnflorescence(s) erect, ± spreading, up to 70(—150) mm long, up to 7 simultaneously, usually ± dense, each with up to 15(—20) flowers; peduncle short, up to 10 mm long; rachis subflexuose, terete, apically ± angular; bracts sheathing, acute, 1-nerved, 1.0-1.6 (-3.0) mm long, transparent yellow-brown. Pedicel short, up to 2.0(—3.2) mm long; ovary ± curved and twisted, (0.7-) 1.1-2.3 x 0.6-0.7 mm. Flowers mostly twisted into a ± horizontal position, up to 16 mm long including ovary and pedicel; whitish, tepals with an orange-brown to salmon-coloured central band or not, spur apex orange-brown, anther yellowish. Glandular hairs sparsely scattered on ovary and base of tepals. Dorsal sepal narrowly oblong, acuminate, subapiculate, with a slightly bulging central area, 3-nerved, (5.0-)5.5-7.3 x 1.5—2.2(-2.7) mm. Lateral sepals slightly asymmetric, narrowly oblong, acuminate, ± apicu-late, 3-nerved, (6.2-)6.4-8.4 (-9.7) x (1.0—) 1.2-1.9 mm. Petals slightly asymmetric, ovate to narrowly ovate, ± apiculate, apically ± erose, 1-nerved, (4.9-)5.2-6.2 (-6.5) x ( 1.4-) 1.6-2.0 (-2.3) mm. Labellum large, indistinctly 3-lobed; mid-lobe broadly ovate, acute to acuminate or obtuse, subapiculate or not, ± flat with upfolded margins, ± erose, 5-nerved, lateral nerves with side-nerves; side-lobes indistinct, ± oblong, with thickenings at each side ± constricting the spur mouth, (5.0—)5.8—7.0 (-7.3) x (3.9-)4.1-5.1 (-5.5) mm; spur long, variously incurved, cylindric, tapering to a ± conical inflation, up to 7.1 mm long, apical inflation up to 0.8 mm in diameter. Column long, ± straight to slightly recurved, 1.7-2.5 mm long, (0.5—)0.7—0.9(—1.0) mm high, pale cream-yellow; androclinium shallowly excavated, with an obtuse pillar-shaped thickening tapering to the rostellum; rostellum-lobes short, ± porrect, fleshy, obtuse, up to 0.6 mm long. Anther ± oblong in outline; in side view ± hemispherical, dorsally bivalvate, tapering into a channelled ± incurved prolongation, apex obtuse, recurved, 2.0-2.5 x 0.9-1.2 mm. Pollinia asymmetric; in side view broadly elliptic to rounded oblong, (450—)490—610(—630) x 380-470 (-500)in median section elliptic oblong, up to 420µm thick. Stipes long, ligulate, channelled, ± spathulate apically, at the very apex geniculate, (1.6—)1.9—2.4 mm long, apically, 0.3-0.4 mm wide. Viscidium linear, with a recurved apex, 600-770 (-860) x 90-120 (-130) µm. Capsule ± narrowly cylindric, straight to slightly curved, 7-15x2-4 mm; pedicel short. Seeds bottle-shaped to ± fusiform, testa cells narrowly elongate (in a dry state), with ± club-shaped and scattered hook-shaped processes; anticlinal walls ± sulcate with finer striations, terminal ends indistinctly protruding, (230-)310-420(-480) x (40-)50-570 µm. Scent distinct, distasteful, slightly reminding of decomposing proteins, with a nocturnal periodicity.
Habitat:
Mainly in the transition zones to lowland rain forest, riverine forest, dry evergreen forest and occasionally extending into woodland in more or less misty conditions. Epiphytic in the crown of high forest trees, or at various heights on understorey trees, also found on different bushes, mostly on finer branches and twigs in the vicinity of water. Altitude. (200—)670—1500 m.
Flowering period:
Mainly located to the transitions between the dry and rainy seasons.
Cultivation:
As given for the genus, warm to cool growing epiphyte.
Distribution:
Nigeria to Kenya and Zambia
References:
Orchids of East Africa Piers 1968; The Orchids of South Central Africa Williamson 1977; A Monograph of the Genus Microcoelia [Orchidaceae] Jonsson 1981; Flora of Tropical East Africa Orchidaceae Part 3 Cribb 1989; Orchids of Kenya Stewart & Campbell 1996; 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:
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In culture In culture
Microcoelia koehleri  01 Microcoelia koehleri  02
Photograph ©Gilles Grunenwald. Image used with kind permission. Photograph ©Gilles Grunenwald. Image used with kind permission.