AFRICAN

ORCHIDS

Orestias elegans Ridl., J. Linn. Soc., Bot. 24: 198 (1888).
Description:
Plants (15 -) 20 - 26 (- 30) cm tall. Rhizome few mm long between shoots, 2 - 3.5 mm Ø, creeping, delicate, sometimes branched, node scales loose. Leafy stem (5)6- 10 (- 14) cm long, (0.12 -) 0.15 - 0.25 (- 0.32) cm Ø; basal scales 1.5 - 2.5 cm long, 0.2 -0.5 cm Ø. Leaves 2-4; leaf petiole (0.2 -) 0.5 - 1.5 (- 1.8) cm long, (0.28 -) 0.35 - 0.5 (- 0.72) cm wide when spread; leaf sheath (0.6 -) 1 - 2 (- 2.8) cm long, (0.3 -) 0.4 - 0.7 (- 0.8) cm Ø, green, sometime fawn tinged; leaf blade (3 -) 4 - 5.2 cm long, 1.2 - 2.8 cm wide, ovate to oblong ovate, older sometime nearly broadly ovate, distinctly attenuate, apiculate at apex, green above, paler beneath. Inflorescence 10 - 16 cm long; raceme (3 -) 4 - 8 (- 11) cm tall, 10 - 40-flowered, dense; peduncle (4 -) 5 - 8 (- 9) cm long. Sterile bracts about 3 - 5, 4.7 - 6 mm long, 1.8 - 2.5 mm wide. Floral bracts 2 - 4.5 mm long, 0.8 -1.6 mm wide. Ovary 1.5-3 mm long, 0.4 - 0.6 mm Ø; pedicel 2 - 2.5 mm long, 0.3 - 0.4 mm Ø; sinuate, green. Flowers (5.5 -) 6 - 6.5 mm Ø; pale green to yellowish green tinged with red or chocolate, or pale cream-pink to dark red, purple-red, brownish red. Dorsal sepal 3.8 - 4 mm long, (1.8)2 - 2.5 mm wide, erect, oblong ovate. Lateral sepals 2.8 - 3 mm long, (1.8 -) 2 - 2.3 mm wide. Petals (3.3 -) 3.5 - 4 mm long, (1.2 -) 1.4 - 1.5 mm wide. Lip 2.2 - 2.6 mm long, 2 - 2.6 mm wide, reaching up to 3/4 - 5/6 of lateral sepals length; lamina nearly quadrate; basal auricles often with involute edges; the middle part of lamina broadly concave, with characteristic convexity below of basal auricles ends - only 1 pubescent cushion - reniform with deep cleft at down edge, middle part of upper edge dark and intense coloured; lamina truncate at distal margins, sometimes weakly indentate with apiculate apex. Gynostemium 1.6 - 2 mm long, column 0.5- 0.7 mm wide; rostellum 0.8 - 1 mm long, 0.3 - 0.35 mm wide, transversely oblong, basal edge narrowly incurved; stigma in widely opened, narrow, deep pocket; anther 0.3- 0.4 mm long, ca. 0.6 mm wide, 0.3 - 0.35 mm high, trapezoid, the distal edge longer; loculi quite separate from each other. Fruit 6-8 mm long, 4-6 mm Ø.
Habitat:
Terrestrial; on yellow clay, in leaflitter, in wet and deeply shaded places, often along streams; in primary, dense, mountain forest; in primary humid and dark lowlands forest, between minute mosses; sometimes noted at secondary forest on ancient plantations. At times described as very common. Alt.: 1050 - 1800 m.
Notes:
Colour of flowers varies from yellowish green and pale cream-pink to dark red, purple-red, and brownish red. Colour of flower depends probably on quantity of light at locality. Flowers of plants growing in lighter places were noted as darker and more intensively coloured.
Summerhayes (1937) mentioned that the floral structure of O. elegans and O. stelidostachya is identical, comparing his newly described O. micrantha with O. stelidostachya, as he understood this species. He recorded for O. stelidostachya that there is "usually one large pubescent spot, which is sometimes represented by two distinct ones". However, spots are much nearer the base of the lip and closer together than in O. micrantha. Exactly these differences of lip convexity, amongst many others are the differentiating characters between O. elegans and (). stelidostachya (see description of species and the key). Therefore, O. elegans cannot be treated as synonym of O. stelidostachya.
Distribution:
São Tomé, Príncipe
References:
Margonska HB, Szlachetko DL. 2005 Taxonomic revision of the African genus Orestias Ridl. (Malaxidinae, Orchidaceae). Ann. Naturhist. Mus. Wien, 107B. 209-220
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