Tridactyle exellii P.J.Cribb & Stévart, Kew Bull. 59: 195 (2004).
Description:
Epiphytic herb; stem 4.5 - 21 cm long, 4 - 6 mm in diameter, spreading or erect, partially covered with old leaf base; roots up to 11, smooth, 2 - 3 mm in diameter. Leaves 3 - 6, oblong to linear, distichous, erect, slightly narrowed before the apex, thin textured, usually forming a fan, 5.4 - 9.8 x 1 - 1.5 cm, unequally roundly bilobed, lobes 1 - 10 mm long, articulate at the base to a sheathing leaf. Inflorescences 1 - 3, suberect, arising at the base of the plant, 4 - 8.5 cm long, 13 - 15-flowered; rachis hemi terete. Flowers distichous, pale greenish-white; pedicel and ovary 2.5- 3 mm long, twisted at the base, papillose; bracts triangular, 3 x 1 mm, amplexicaul. Dorsal sepal ovate, 3 x 1.8 - 1.9 mm, uninerved, acute and slightly apiculate, slightly papillose on outer face. Lateral sepals obliquely ovate-triangular, 3.4 - 4 x 2 mm, acuminate, slightly united at the base to the other lateral sepal, papillose and keeled on the outer face. Petals narrowly triangular, 2.8 x 1.2 mm, apex apiculate, uninerved. Lip transversally oblong to obovate, trilobed in the Apical part, 2.5 - 3 x 3 - 3.5 mm, auriculate at the base; side lobes very short, 1 mm wide, erose to unequally 2 - 4-laciniate; midlobe narrowly triangular, 1 mm long, curving downwards; spur slightly curved, compressed, slightly swollen at the apex, 9 x 1 - 1.2 mm, apex obtuse. Column very short.
Etymology:
This species is named in honour of the British botanist Arthur Wallace Exell for his valuable contribution to our knowledge of the floras of the Gulf of Guinea islands.
Habitat:
Evergreen mist-forest and open vegetation on mountain ridges; 900 - 1610 m. Epiphyte in sunny or mid-shade conditions on shrubs or trees, in particular on Homalium henriquensii Gilg, Syzygium guineense DC. and Olea capensis L. This species lives on branches 3 - 10 cm in diameter amongst mosses and ferns; some specimens are found on bare bark or branches with significant humus deposits.
Cultivation:
As given for the genus.
Notes:
It can be distinguished from other Tridactyle species by its leaves which are ovate and slightly narrowed below the apex which is broader.
Distribution:
São Tomé, Gabon
References:
World Checklist of Monocotyledons. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/monocots/ accessed 21.03.2017
Images:
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