Genus Centrostigma

Centrostigma papillosum Summerh., Kew Bull. 11: 219 (1956).
Description:
A slender herb 40–65 cm tall, drying dark brown or almost black; tubers ellipsoid. Stem leafy; leaves 6–8, the two lowest sheathing, the rest semi- erect, up to c. 9 × 1.5 cm, lanceolate, acute. Inflorescence 11–20 × 3.5–4 cm, laxly 2–12-flowered; ovary and pedicel c. 35 mm long; bracts of similar length. Flowers green. Dorsal sepal erect, 10.5–12 × 4–8 mm, ovate, convex; lateral sepals sharply reflexed and curled, 10–11 × 2.5–4 mm, obliquely lanceolate. Petals 7–12 × 1–3 mm, lanceolate, obtuse, usually with a small lateral lobe near the base, lying inside dorsal sepal. Lip 3-lobed; claw 2–4 mm long; mid-lobe 10–13 × 1–2.5 mm, linear, reflexed; side lobes 10–13 × 2–3 mm, projecting forwards, the apex truncate and dentate. Spur 20–25 mm long, tucked into bract. Anther 2.8–3 mm high; canals 3–4 mm long. Stigmatic arms 3–5 mm long.
Habitat:
Dambo and marshy areas 1300–1500 m.
Distribution:
S. Trop. Africa

Centrostigma occultans (Welw. ex Rchb.f.) Schltr., Bot. Jahrb. Syst. 53: 523 (1915).
Homotypic Synonyms:
Habenaria occultans Welw. ex Rchb.f., Flora 48: 178 (1865).
Heterotypic Synonyms:
Habenaria schlechteri Kraenzl. ex Schltr., Bot. Jahrb. Syst. 20(50): 35 (1895).
Centrostigma nyassanum Schltr., Bot. Jahrb. Syst. 53: 523 (1915).
Centrostigma schlechteri (Kraenzl. ex Schltr.) Schltr., Bot. Jahrb. Syst. 53: 523 (1915).
Description:
A terrestrial herb 4-7 dm. high, glabrous except for the roots; tubers globose to almost cylindrical, 1-2.5 cm. long, 0.5-1 cm. in diameter, glabrous or sparsely hairy; roots flexuous, slender, ± hairy. Stem erect, slender to rather stout, up to 7 mm. diameter at base, leafy throughout its length, somewhat angular. Leaves 7-10, the lowermost 1 or 2 reduced to tight sheaths, the remainder erect or suberect, narrowly lanceolate or linear, acute or acuminate, the largest 8-16 cm. long and 1-2 cm. broad, the uppermost ones similar to the bracts. Inflorescence 6-16 cm. long, 5-7 cm. in diameter, rather closely 3-10-flowered. Bracts erect, leafy, lanceolate, acute, 3-6 cm. long, often longer than the pedicel with ovary. Flowers suberect or curving outwards, green, greenish-white or greenish-yellow; pedicel with ovary rather slender, slightly curved, 4.5-6 cm. long, lengthening in fruit. Dorsal sepal erect, broadly ovate, acuminate, apex recurved, very convex, 15-18 mm. long, 10-15 mm. broad; laterals decurved, obliquely and narrowly lanceolate, acuminate, 14-18 mm. long, 4-6 mm. broad, somewhat twisted, 3-nerved. Petals erect, much curved, obliquely lanceolate, acute, 14-17 mm. long, ± 4 mm. broad, 2-nerved. Lip united for 3-4 mm. at the base to the column, free part 3-lobed nearly to the base ; middle lobe deflexed, linear-lanceolate, acute, 16-21 mm. long, 2-3 mm. broad; side lobes spreading, oblanceolate-linear in general shape, the apical part divided into 7-10 slender filaments or bearing similar filaments along the outer margin, as long as the middle lobe, ± 3 mm. broad; spur dependent, narrowly cylindrical, apical third very slightly swollen, 10-15 cm. long, scarcely 2 mm. in diameter. Anther erect, apiculate, 8-11 mm. high, loculi contiguous, parallel, canals slender, ± I cm. long; stigmatic processes bilobed above the base, the lower lobe horizontal, stout, obliquely clavate at the apex, whole length from base 8-9 mm., the upper lobe very slender, horn-like, tapering, curving up in front of the column, 7-9 mm. from its junction with the lower lobe (there is sometimes a much smaller additional lobe arising from the outside of the lower lobe), rostellum middle lobe erect, narrowly triangular, acute, 3-5 mm. high, the side lobes horizontal and attached to the lip in the basal half, curving upwards in the apical half, ± 1 cm. long.
Habitat:
Dambo and marshy localities 1250–1700 m.
Cultivation:
Not in cultivation
Distribution:
Tanzania to Angola and Northern Prov.
References:
Flora of Tropical East Africa Summerhayes Orchidaceae Part 1 1968; Flora Zambesiaca Vol 11, Part 1, (1995) Author: I. la Croix and P.J. Cribb; African Orchids: XXIII V. S. Summerhayes, Kew Bulletin, Vol. 11, No. 2 (1956), pp. 217-236; African Orchids: VI V. S. Summerhayes, Bulletin of Miscellaneous Information (Royal Gardens, Kew), Vol. 1934, No. 5 (1934), pp. 205-214
Images:
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Habitat/In situ	Habitat/In situ	Habitat/In situ	Habitat/In situ

Photograph© Lourens Grobler. Image used with kind permission.	Photograph© Lourens Grobler. Image used with kind permission.	Photograph© Lourens Grobler. Image used with kind permission.	Photograph© Lourens Grobler. Image used with kind permission.

Centrostigma clavatum Summerh., Kew Bull. 11: 221 (1956).
Description:
Stern 50-60 cm tall, erect, robust, glabrous. Leaves 6-7, up to 14 cm long and 2 cm wide, the largest in the middle, semi-erect, lanceolate, acute, ribbed. Inflorescence 5-32 cm long, loosely 4-18-flowered. Flowers white, greenish-cream or greenish-yellow. Floral bracts up to 95 mm long. Pedicel and ovary up to 60 mm long. Dorsal sepal 16.5-20 mm long, 11-13 mm wide, ovate-lanceolate, acute, concave, puberulous at the apex. Petals 17-20 mm long, 5-6 mm wide, linear-lanceolate, acute, falcate, ciliolate in upper half. Lateral sepals 20-22.5 mm long, 5-6.5 mm wide, obliquely lanceolate, spreading, acute, apical parts puberulous. Lip 3-lobed, claw 4-4.5 mm long, attached to the base of gynostemium and lateral sepals; the middle lobe 20-30 mm long, 1.5-3 mm wide, linear-lanceolate, acute, deflexed; lateral lobes 25-35 mm long, 2-4 mm wide, ligulate, swept forwards, with pectinations ca. 5 mm long in apical half. Spur 55-75 mm long, cylindrical, swollen at the apex, usually tucked into the bract.
Habitat:
In dambo, swampy grasslands. December-January.
Cultivation:
Not in cultivation, warm to cool growing terrestrial.
Distribution:
The Democratic Republic of Congo (Zaire), Tanzania, Malawi and Zambia. Alt. 1200-1680 m.
References:
Orchidaceae of West-central Africa, vol. 1, Gdansk University Press Gdansk 2010; Flora of Tropical East Africa Part 1 Summerhayes 1968; The Orchids of South Central Africa Williamson 1977, Flora Zambesiaca Vol 11 Part 2 Pope 1998
Images:
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Habitat/In situ	Habitat/In situ	Habitat/In situ

Photograph© Nicholas Case Wightman Image used with kind permission.	Photograph© Nicholas Case Wightman Image used with kind permission.	Photograph© Nicholas Case Wightman Image used with kind permission.