AFRICAN

ORCHIDS

Key to the species of Margelliantha P.J.Cribb

1 Spur 12-17 mm long, leaves occasionally absent or linear-lorate, 2.5-6.5 x 0.5-0.8 cm, flowers white (South Africa) M.caffra
1a Spur not exceeding 10 mm, leaves different, flowers white or pale green to pale yellow 2
2 Leaves more than 10 cm long and 1.5 cm wide, broadest towards apex, spur 10 mm long, flowers white with green anther-cap (Congo, Rwanda) M. burtii
2a Leaves less than 10 cm long and 1 cm wide, not broadening towards apex, spur less than 8 mm long, flowers white or creamy to greenish yellow 3
3 Spur almost globose, 4 mm long and 2.5-3mm in diameter, bracts somewhat inflated, 3.5 mm long and 3 mm wide, flowers creamy yellow (Tanzania) M.globularis
3a Spur clavate or clavate-elongate, 6-7 mm long, not exceeding 2 mm in diameter, bracts inconspicuous, less than 2.5 mm long and wide, flowers white or pale greenish yellow 4
4 Spur distinctly curved, up to 7 mm long, slightly clavate, flowers white with white anther-cap, leaves very succulent, up to 2.5 mm thick, distinctly unequally lobed at apex, one lobe exceeding the other by 8 mm (Rwanda) M.lebelii
4a Spur not or only slightly curved, distinctly clavate, flowers white with green anther-cap or pale greenish yellow, leaves not or only slightly succulent, never exceeding 1 mm height in transversal section, apex slightly unequally bilobed, one lobe exceeding the other by only 1-2 mm 5
5 Flowers glistening white with a green anther cap, spur slightly incurved, 2 mm in diameter at apex, lateral sepals falcate, sepals more than 4.5 mm long, lip more than 5 mm long, 6-8 mm wide (Kenya, Tanzania) M.leedalii
5a Flowers pale greenish yellow, spur straight, relatively slender, less than 1.2 mm in diameter, lateral sepals not markedly falcate, sepals 3-3.5 mm long, lip 4 mm long and 5.5 mm wide (Tanzania) M.clavate

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 18.03.2017