AFRICAN

ORCHIDS

Microcoelia exilis Lindl., Gen. Sp. Orchid. Pl.: 61 (1830).
Homotypic Synonyms:
Gussonea exilis (Lindl.) Ridl., J. Linn. Soc., Bot. 21: 493 (1885).
Epidorchis exilis (Lindl.) Kuntze, Revis. Gen. Pl. 2: 660 (1891).
Mystacidium exile (Lindl.) T.Durand & Schinz, Consp. Fl. Afric. 5: 52 (1894).
Heterotypic Synonyms:
Angraecum chiloschistae Rchb.f., Linnaea 20: 678 (1847).
Rhaphidorhynchus chiloschistae (Rchb.f.) Finet, Bull. Soc. Bot. France 54(9): 35 (1907).
Gussonea chiloschistae (Rchb.f.) Schltr., Beih. Bot. Centralbl. 36(2): 91 (1918).
Description:
Epiphytic or occasionally epilithic plant. Stem short or long, occasionally proliferous up to 45(—65) x (1.5—) 2 —3(—4) mm. Scale-leaves rostrate to acuminate, up to 4.5(—6) mm long, with 5—7( —8) nerves. Roots many, slender to ± robust, variously spreading, densley crowded. characteristically twisted and much branched, tightly (when young) to ± loosely (when old) attached to the substrate, terete, ± flattened on the lower side when attached to the substrate, smooth, up to 35(—45) cm x (0.5—)1.0—2.0 mm, when living having a silvery greenish grey lustre in a ± dry state. Inflorescence(s) ± erect or pendulous, up to 250 mm long, up to 10—20(—40) simultaneously, usually dense, each with up to 45-50(-80) flowers; peduncle short, up to 30 mm long; rachis ± straight to indistinctly flexuose, slightly angular, ± finely ribbed, (Scheele's green) or fading into (orange-brown); bracts not sheathing, ± triangular to ovate, acute, basal indistinctly 3-nerved, apical indistinctly 1-nerved, (0.2—)0.6-1.2 (-2.6) mm, (flesh ocher) fading into (vinaceous rufous) or ± transparent towards the apex of rachis. Pedicel indistinct; ovary sessile or subsessile when mature, (0.2—)0.5-1.0 (-1.9) x 0.2-0.6(-0.9) mm, (Scheele's green) or tinged with (salmon orange) or (straw yellow to dull green-yellow). Flowers ± erect to descending, spreading, up to 4.2 mm long including ovary and pedicel; ovary yellow-green, orange-yellow, salmon or light yellow; perianth pure white, at base fading into the colour of the ovary; spur whitish, apex fading into light yellow-green. Glandular hairs very sparsely present on rachis and ovary, base of bracts and tepals. Tepals ± convex, slightly connate at the very base, with a single thickened nerve. Dorsal sepal obovate, obtuse to subacute, (0.7—) 1.0—1.5(—2.3) x 0.4—0.9(—1.3) mm. Lateral sepals slightly asymmetric, obovate, obtuse to subacute, (0.7—) 1.0—1.5 (—2.3) x 0.4—0.8(—1.3) mm. Petals obovate to ± ovate, obtuse to subacuminate, 0.6—1.2(—1.7) x 0.3—0.7(—1.3) mm. Labellum short, rounded to semiorbicular, concave to ± plated, indistinctly 3-nerved, 0.6—1.1(—1.9) x 0.4—0.8(—1.3) mm; spur small, globose or slightly compressed apically to ± obtusely cylindric, (0.4-)0.6-0.9 (—1.3) x 0.5—1.()(—1.6) mm, apically fading into (pale yellow-green and viridine green). Column short, truncate, 0.2-0.5(-0.9) mm long, 0.2 - 0.6(—1.1) mm high, (Scheele's green) tinged with (Peacock's green) or (olive green to oil yellow); androclinium shallowly excavated, with a small hump in the centre; rostel-lum-lobes ± inflexed, ± rectangular, up to 0.25 mm long, whitish. Anther ± semicordate in side view, frontally ± flattened, slightly bilobed dorsally, tapering into a truncately rounded apex, 0.4—0.6(—1.1) x 0.2-0.6(-0.9) mm, (Scheele's green) fading into (Peacock's green) with a central dorsal patch ( ± Kaiser brown). Pollinia ± ellipsoid, asymmetric; in side view obovate to ± pyriform, (170-)200-270 (-440) x (130-) 145-200 (-300) µm; in median section elliptic, up to 110-140 pm thick, (empire yellow). Stipes ligulate, spathulate apically, sigmoid, (170-) 210-330 (-470) pm long, apically up to 80— 130(— 190) µm wide, whitish fading into (empire yellow) at the apex; viscidium ± rectangular, membranous, (95-) 130-220 (-250) x (60-)70-120 (-160 µm. Capsule turbinate or ellipsoid to ± oblong, (2.6-)3-4 (-6.5) x (1.3—)2—3 mm, pedicel ± indistinct, up to 1.0 mm long. Seeds bottle-shaped to ± cylindrical or fusiform, testa cells narrowly reticulate (in a dry state), with ± club-shaped and hook-shaped processes; anticlinal walls finely furrowed, terminal ends ± elongated, (360—)570—720(—830) x (50—)60—80(—90)µm. Scent not percepte.
Habitat:
Mainly in riverine forest and woodland extending into rain forest and bushland in Madagascar Often found in secondary forest and in plantations. Mostly confined to smaller branches and twigs of understorey trees and bushes in more or less exposed positions, particularly older specimens are often found attached to almost nothing. Altitude. 0-1800 m.
Flowering period:
Throughout the year, with a tendency of concentration at the beginning and end of the rainy seasons.
Cultivation:
No one could call this species showy, but a large plant with its mass of branching roots is always interesting. This species seems to flower off and on throughout the year. It likes only light shade and intermediate to warm conditions.
Notes:
Easily distinguished by the extremely small flowers and almost globular spur.
Distribution:
Kenya to KwaZulu-Natal, S. Madagascar
References:
Flora of Madagascar Perrier 1936/1981; The Orchids of South Central Africa Williamson 1977; A Monograph of the Genus Microcoelia [Orchidaceae] Jonsson 1981; Wild Orchids of Southern Africa Stewart, Linder, Schelpe & Hall 1982; Flora of Tropical East Africa Orchidaceae Part 3 Cribb 1989; Flora Zambesiaca Vol 11 Part 2 Pope 1998; AOS Bulletin Vol 72 No 3 2003; Angraecoid Orchids Stewart, Hermans, Campbell 2006; Orchids of Madagascar Hermans 2007; Field Guide to the Orchids of Northern South Africa and Swaziland McMurty, Grobler, Grobler & Burns 2008; Field Guide to the Orchids of Madagascar Cribb & Herman 2009 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.

In culture In culture In culture
Microcoelia exilis 01 Microcoelia exilis  02 Microcoelia exilis  03
Photograph ©Gilles Grunenwald. Image used with kind permission. Photograph ©Gilles Grunenwald. Image used with kind permission. Photograph ©Gilles Grunenwald. Image used with kind permission.

 

Habitat/In situ Habitat/In situ
microcoelia exilis 01 microcoelia exilis 02
Photograph©Bart Wursten. Image used with kind permission. Photograph©Bart Wursten. Image used with kind permission.