AFRICAN

ORCHIDS

Microcoelia globulosa (Hochst.) L.Jonss., Symb. Bot. Upsal. 23: 78 (1981).
Homotypic Synonyms:
Angraecum globulosum Hochst., Exsicc. (Schimp.) 3: 1565 (1844).
Gussonea globulosa (Hochst.) Ridl., J. Linn. Soc., Bot. 21: 491 (1885).
Mystacidium globulosum (Hochst.) T.Durand & Schinz, Consp. Fl. Afric. 5: 53 (1894).
Heterotypic Synonyms:
Angraecum guyonianum Rchb.f., Linnaea 22: 865 (1850).
Microcaelia taeniophyllum Hochst. ex A.Rich., Tent. Fl. Abyss. 2: 285 (1850).
Saccolabium radicosum A.Rich., Tent. Fl. Abyss. 2: 285 (1850).
Aeranthes guyoniana (Rchb.f.) Rchb.f., Flora 48: 190 (1865).
Epidorchis guoyaniana (Rchb.f.) Kuntze, Revis. Gen. Pl. 2: 660 (1891).
Mystacidium radicosum T.Durand & Schinz, Consp. Fl. Afric. 5: 54 (1894).
Microcoelia guyoniana (Rchb.f.) Summerh., Bot. Mus. Leafl. 11: 144 (1943).
Description:
Epiphytic plant. Stem short or ± long, (2-)35-65 (—85) x (l-)2-3(-4.5) mm. Scale-leaves acuminate to obtuse, up to 3.5 mm long, with (4—)5—7 nerves. Roots few to many, ± short and radially spreading, densely crowded and occasionally clustered in a ± conical-shaped bundle, often characteristically undulating and twisting with a ± stiff appearance, occasionally with few branches, mostly loosely attached to the substrate, ± terete, smooth, up to 35 cmxl.0-2.0 (-3.0) mm, when living having a silvery light-green lustre in a ± dry state. Inflorescence(s) ± stiff, erect or descending, ± spreading, up to (20—)90 mm long, up to 5—10(—20) simultaneously, usually sparse, each with up to 15(—26) flowers; peduncle short, up to 15 mm long, rachis ± flexuose, variously furrowed and excavated with ± well developed hook-shaped processes below the bracts, (Scheele's green); bracts at base sheathing, progressively not sheathing towards the apex of rachis, ovate, acute to subacuminate, indistinctly 1-nerved, up to 2.5(—3.0) mm long, (flesh ocher). Pedicel distinct, forming a ± distinct angle to the ovary, slightly furrowed, up to 3 mm long, (light yellow-green); ovary ± straight, distinctly furrowed (0.8-)3.0x0.3-0.8 mm, (pale olive-buff) with the furrows tinged with (vinaceous-rufous). Flowers ± horizontal, up to 10 mm long including ovary and pedicel; perianth pure white, at the base fading into the colour of the ovary; labellum pure white, basally yellow green; spur whitish, apically fading into dark green, orange-brown at the very tip; anther golden brown; column greenish brown. Glandular hairs very sparse, on rachis, pedicel, ovary and at the base of bracts and perianth. Dorsal sepal slightly convex, ovate, acute, ± apiculate, 1- to indistinctly 3-nerved, with a ± distinct outer central groove, (1.6—)2.2-3.1 (—3.7) x (0.6—) 1.0—1.4 mm. Lateral sepals ovate to narrowly ovate, acute, ± apiculate, with (1—)3 nerves, distinctly thickened along the central nerve, (1.7-) 2.5—3.5(—4.1) x (0.6—)0.9—1.3(-l .8) mm. Petals ± obovate to elliptic, acute, ± apiculate, with 1 nerve, narrowly thickened along the central nerve, (1.3-)2.1—3.0(—3.6)x(0.6—)0.8—1 -2(—1.6) mm. Labellum pandurate; mid-lobe apically ± folded, with a ± distinct cushion-like thickening at each side of spur mouth, occasionally with an elongated central thickening, 3-nerved, with sparsely branched outer nerves; side-lobes small, rounded, (1,4-)2.2-3.3(-4.1) x (0.6—) 1.2— 1.8(—2.4) mm, around spur mouth fading into (oil yellow); spur characteristically incurved or occasionally decurved; base ± conical, tapering to a geniculate cylindric apical part, apex obtuse and slightly inflexed, (1.6—)2.1-3.1(—3.7) mm long, up to 0.6 mm in diameter apically, at base (oil yellow) successively fading into (aniline yellow), or when old (xanthine orange) apically. Column short, truncate, outer sides ± concave, 0.3-0.6(-0.8) mm long, (0.6—)0.7—0.9(— 1.1) mm high, (oil green); androclinium shallowly excavated, with a ridge-like hump in the centre; rostellum lobes ± perpendicular to slightly protruding, ± rectangular, 0.3-0.5(0.6) mm long, transparent-whitish. Anther ± semicordate in side view, proximally bivalved, tapering into a truncate shortly recurved and ± apiculate apex, (0.5-) 0.6-0.8(-0.9) x (0.4-)0.6-0.8(-0.9) mm, (orange-rufous), apical rim whitish. Pollinia subglobose, asymmetric; in side view semiorbicular to elliptic, (310-)340-410(-450) x (250-)300-350(-400) µm; in median section ovate to semiovate, up to 250(-300 µthick, (primrose yellow). Stipes ligulate, spathulate apically, sigmoid, (170—)240— 370(—500) µm long, 80-110(-140),Mm wide at the apex, transparent; viscidium ± rectangular, posterior end rounded, membranous, transparent, (160-) 190-320(-410) x(80-) 100-160 µm. Capsule slightly curved to straight, ellipsoid to cylindrical, 4-8(-12)x 2-3 mm; pedicel distinct, up to 3 mm long. Seeds bottle-shaped to cylindrical or fusiform, testa cells narrowly elongate (in a dry state), with ± club-shaped and more sparsely with hook-shaped processes; anticlinal walls furrowed, at the terminal ends ± elongated, (270—)390—510(—620) x(40—)50—80(—120) µm. Scent distinct, fragrant, freshly sweet, ± near the smell of honey, in some specimens the scent is so heavy that it feels pungent.
Habitat:
Margins of evergreen forest and in relict rain forest, riverine forest extending into wooded-grassland and in secondary vegetation. Once found in coastal bushland (cf. Moreau 108, Tanzania). Epiphytic in more or less open conditions, usually attached on relatively low height, on trunks, branches and twigs. Altitude. (0-)500— 1950 m.
Flowering period:
Mainly recorded during the transitions between the rainy and dry seasons, starting in the northernmost area of distribution at the early rainy/dry season, successively moving to the late dry/rainy season of the southernmost area of distribution.
Cultivation:
As given for the genus, warm to cool growing epiphyte.
Distribution:
Nigeria to Eritrea and S. Trop. Africa
References:
Encyclopedia of Cultivated Orchids Hawkes 1965; Orchids of East Africa Piers 1968; The Orchids of South Central Africa Williamson 1977; AOS Bulletin Vol 48 No 5 1979; A Monograph of the Genus Microcoelia [Orchidaceae] Jonsson 1981; AOS Bulletin Vol 57 No 2 1988; Flora of Tropical East Africa Orchidaceae Part 3 Cribb 1989; Phylogeny and Classification of the Orchid Family Dressler 1993; AOS Bulletin Vol 72 No 3 2003; Angraecoid Orchids Stewart, Hermans, Campbell 2006; WCSP (2017). 'World Checklist of Selected Plant Families. 03.03-2017; http://apps.kew.org/wcsp/
Images:
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Photograph ©Leo Klemm. Image used with kind permission. Photograph ©Leo Klemm. Image used with kind permission. Photograph ©Leo Klemm. Image used with kind permission. Photograph ©Leo Klemm. Image used with kind permission. Photograph ©Leo Klemm. Image used with kind permission. Photograph ©Leo Klemm. Image used with kind permission. Photograph ©Leo Klemm. Image used with kind permission.