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
Images:
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Orestias micrantha Summerh., Bull. Misc. Inform. Kew 1937: 460 (1937).
Description:
Plants (10 -) 15 - 30 cm tall, few to many compactly clustered. Rhizome few mm long between shoots, 1 - 2.4 mm Ø, sometimes branched, node scales loose. Leafy stem (5 -) 8 - 15 cm long, (0.1 -) 0.15 - 0.25 (- 0.3) cm Ø; basal scales 2-3, (0.6 -) 1 - 2.5 cm long, 0.18 - 0.45 cm Ø. Leaves 3-4; leaf petiole (0.15 -) 0.3 - 0.6 (- 0.8) cm long, (0.28 -) 0.35 - 0.45 (- 0.5) cm wide when spread; leaf sheath (0.5 -) 0.8 - 1.6 (- 2.3) cm long, (0.3 -) 0.4 - 0.6 cm Ø, green, sometimes paler, fawn tinged; leaf blade (1.5 -) 2 - 6 (- 6.5) cm long, (1 -) 1.5 - 3 (- 3.2) cm wide, broadly ovate, ovate to oblong ovate, apiculate at apex, green above, paler beneath. Inflorescence (8 -) 10-22 cm long; raceme (3 -) 5 - 14 cm tall, 30 - 50 (- 60)-flowered; peduncle 5 - 8 cm long. Sterile bracts about 3 - 6, 2 - 35 mm long, 1.5-2 mm wide. Floral bracts 1.2-2 mm long, 0.6 - 1.3 mm wide. Ovary 0.6 - 1.5 mm long, 0.4 - 0.8 mm 0; pedicel 0.4 - 1 (- 2) mm long, 0.2 - 0.4 mm 0; sinuate, green. Flowers 5-5.2 mm long, ca. 4 mm wide; white and green, tinged with red or brown, to dark purple, lip yellowish to whole mauve to purple. Dorsal sepal 2.5 - 3 mm long, 1.2 - 1.4 mm wide, erect, oblong ovate to oblong. Lateral sepals 2.1 - 2.4 mm long, 1.4 - 1.6 mm wide. Petals 2.6 - 2.8 mm long, 0.7 - 0.8 mm wide, external margin delicately ciliate. Lip (1.5 -) 1.7 - 1.8 mm long, 2.2 - 2.5 mm wide, broader than long, reaching out about 2/3 - 3/4 length of lateral sepals; lamina nearly octagonal in outline; basal auricles well developed, often with involuted edges; the middle part of lamina broadly, slightly depressed, characteristic convexities - 2 pubescent, symmetrical, reniforme cushions - reaching out of down edges of basal auricles of lip; distal margins of lamina nearly truncate, with round apex at the middle part. Gynostemium 1.1 -1.4 mm long; column 0.4 - 0.5 mm wide at base; rostellum 0.7 - 0.8 mm long, 0.4 - 0.5 mm wide, transversely flabellate, basal edge narrowly incurved; stigma in widely opened, deep pocket; anther 0.4 - 0.5 mm long, 0.45 - 0.5 mm wide, 0.25 - 0.3 mm high, slightly hexagonal; loculi well separated from each other. Fruit 4.5 - 6 mm long, 23-5 mm Ø.
Habitat:
Terrestrial; in leaflitter, in forests. Alt.: 450 - 1800m.
Note:
Stanford (mscr.) mentioned that petals of the species have ciliolate margins. The cilia are very thin and delicate. Therefore, sometimes in worse preserved (dry or even conserved in liquid) materials ciliation can be hardly visible.
Distribution:
São Tomé, S. Cameroon to Equatorial Guinea
References:
Exell A.W., 1944: Catalogue of the vascular plants of S. Tome (with Principe and Annobon): 320-321. - London: British Museum.
Summerhayes 1937: Africa Orchid, 9. - Kew Bull. 1937: 457-466.
Summerhayes 1956: - In Troupin, FI. Spermolt. Parc Nat. Garamba (Explor. Parc Nat. Garamba Miss. H. de Saeger, Fasc. 4.) 1. Gymnosp. & Monocot.: 258.
Szlachetko D.L, Margonska H.B., Kras M & Kowalkowska A., 2006 (in press): Contribution to the Orchid flora of West Central Africa. Vol. 2. - Krakow. Institut of Botany, Polish Academy of Sciences.
Szlachetko & Olszewski (2001). Orchidaceae. - In: Morat P. (ed.): Flore du Cameroun 2. 36: 322-670 + 130 maps. - Paris: Museum National d’Histoire naturelle & Yaounde: Herbier National.
Images:
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Orestias stelidostachya (Rchb.f.) Summerh., Bull. Misc. Inform. Kew 1937: 460 (1937).
Homotypic Synonyms:
Microstylis stelidostachya Rchb.f., Otia Bot. Hamburg.: 118 (1881).
Malaxis stelidostachya (Rchb.f.) Kuntze, Revis. Gen. Pl. 2: 673 (1891).
Description:
Plants (10 -) 15 - 25 (- 28) cm tall, few to many compactly clustered. Rhizome few mm long between shoots, 1.8 - 3.6 mm Ø, sometimes branched, node scales loose. Leafy stem (4 -) 6 - 10 (- 12) cm long, (0.13 -) 0.2 - 0.26 (- 0.3) cm Ø; basal scales 1.6 - 2.8 cm long, 0.2 - 0.55 cm 0. Leaves (2 -) 3 (- 4); leaf petiole (0.2 -) 0.4 - 0.8 (- 1.4) cm long, (0.3 -) 0.4 - 0.5 (- 0.65) cm wide when spread; leaf sheath (0.6 -) 1 - 2 (- 2.8) cm long, (0.15 -) 0.3 - 0.4 (- 0.5) cm Ø, green, sometimes fawn tinged; leaf blade (2.8 -) 5.5 - 6.5 (- 7) cm long, (2.4 -) 3 - 4 (- 5) cm wide, broadly ovate, ovate to oblong ovate, apiculate at apex, green above, paler beneath. Inflorescence (6 -) 9 - 16 cm long; raceme (3 -) 4 - 8 (- 10) cm tall, 10 - 40-flowered; peduncle (3 -) 5 - 6 (- 7) cm long. Sterile bracts about 3-6,4.6 - 6.5 mm long, 1.8 - 2.6 mm wide. Floral bracts 1.8 - 4.5 mm long, 0.8 - 1.7 mm wide. Ovary 1.5 - 3.6 mm long, 0.4 - 0.65 mm 0; pedicel 2-3 mm long, 0.3 - 0.5 mm 0; sinuate, green. Flowers (5.6 -) 6 - 7.2 mm 0; white and green tinged with red or brown, to purple-red (particularly lip with intensively coloured spot). Dorsal sepal 3.8 - 4.2 mm long, (1.8 -) 2 - 2.6 mm wide, erect, oblong ovate to oblong. Lateral sepals 2.8 - 3.2 mm long, (1.8 -) 2 - 2.4 mm wide. Petals (3.3 -) 3.5 - 4 mm long, (1.2 -) 1.4 - 1.5 mm wide. Lip 2.7 - 3.3 mm long, 2.4 - 3 mm wide, longer than broader and than lateral sepals length; lamina peariform in outline; basal auricles often with involute edges; the middle part of lamina broadly depressed, just below the lip base with characteristic convexities - 2 pubescent, symmetrical cushions - each of them reniform, with dark and intensively coloured spot; lamina at distal margins deeply cleft, each sublobe obliquely truncate, with minute apiculate apex between them. Gynostemium 1.2 - 1.8 mm long; column 0.4 - 0.6 mm wide at base; rostellum 0.75 - 0.9 mm long, 0.25 - 0.32 mm wide, transversely flabellate to fishfinlike with gently indentation at the middle of distal margin, basal edge narrowly incurved; stigma in widely opened, narrow, deep pocket; anther 0.25 - 0.3 mm long, 0.32 - 0.4 mm wide, 0.25 - 0.3 mm high, trapezoid, the distal edge shorter; loculi distinctly separated from each other. Fruit 5.8 - 7.8 mm long, 3.5 - 5.6 mm Ø.
Habitat:
Terrestrial; in leaflitter; in primary humid lowlands forest, amongst minute mosses; in primary, dense humid, mountain forest; sometimes between Cyperus papyrus; also found in secondary forest on ancient plantations. Alt.: 200 - 1550m.
Note:
Similarly to O. elegans flowers colour probably depends on intensity of light at locality. Flowers of plants growing in lighter places were darker and more intensively coloured.

Amongst all species of the genus O. stelidostachya is characterized by the largest lip, longer than wide, peariform in outline, with deep and distinct cleft at distal margin. Pubescent convexities of lip are placed near its base (weakly reaching out of ends of lip lateral auricles), lip usually completely covering the lateral sepals, as well.
Distribution:
São Tomé
References:
Exell A.W., 1944: Catalogue of the vascular plants of S. Tome (with Principe and Annobon): 320-321. - London: British Museum.
Summerhayes 1937: Africa Orchid, 9. - Kew Bull. 1937: 457-466.
Summerhayes 1956: - In Troupin, FI. Spermolt. Parc Nat. Garamba (Explor. Parc Nat. Garamba Miss. H. de Saeger, Fasc. 4.) 1. Gymnosp. & Monocot.: 258.
Szlachetko D.L, Margonska H.B., Kras M & Kowalkowska A., 2006 (in press): Contribution to the Orchid flora of West Central Africa. Vol. 2. - Krakow. Institut of Botany, Polish Academy of Sciences.
Szlachetko & Olszewski (2001). Orchidaceae. - In: Morat P. (ed.): Flore du Cameroun 2. 36: 322-670 + 130 maps. - Paris: Museum National d’Histoire naturelle & Yaounde: Herbier National.
Images:
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Habitat/In situ	Habitat/In situ	Habitat/In situ
Photograph© João Farminhão/ Missouri Botanical Garden. Image used with kind permission.	Photograph© João Farminhão/ Missouri Botanical Garden. Image used with kind permission.	Photograph© João Farminhão/ Missouri Botanical Garden. Image used with kind permission.