AFRICAN

ORCHIDS

Gastrodia ballii P.J.Cribb & Browning, Kew Bull. 65: 317 (2010).
Description:
A holomycotrophic herb growing from a subterranean fusiform rhizome, 30 – 40 × 9 – 14 mm, each rhizome arising from the apex of the previous one, with a narrow stalk 10mmlong; roots fine, 40 – 50 mmlong, at base of rhizome only. Inflorescence 40 – 60 mm tall, densely racemose; peduncle whitish chocolate brown; leaf scales 3 – 4, appressed, papery, 7 mm long, claret-coloured; fertile bracts ovate, acute, 6 × 2.3 – 3 mm. Flowers resupinate, 1 – 5, borne at right angles to the rachis, campanulate, somewhat rugulose on the outer surface of the sepals, liver-coloured to grey-brown with pale fleshcoloured petals and a yellow green lip with an apricot tip; pedicel and ovary 11 mm long, pedicel lengthening after fertilisation; ovary subtriangular in cross-section, pustulate. Sepals subsimilar, fused into a tube for three-quarters of their length, 12 × 6.5 mm. Petals borne on the sepals where the sepals split, broadly ovate, obtuse or rounded, 2 mm long and broad, erose. Lip fleshy, porrect, ovate, rounded and slightly decurved at apex, 4.5 – 5 × 3 mm; callus somewhat Vshaped, of two incurved ridges united at the front. Column clavate, 7 mm long, with two acute apical stelidia; foot incurved, fused to perianth at the base, with two apical cephaloid tubercular processes. Fruit erect, 33 – 35 mm long, the elongated stalk 10 – 50 cm tall, olive-brown.
Habitat:
In deep leaf mould near rocks in riverine forest of Khaya/Newtonia and Craibia/Newtonia forest in deep shade; 700 – 800 m.
Notes:
This species is undoubtedly close to Gastrodia rwandensis but differs in its flower colour, tiny petals and lip which is ovate and very obscurely 3-lobed and has and inverted V-shaped callus. It has been found in a small area on the Mozambique/Zimbabwe border and also in southern Malawi. Because of its ephemeral nature, being seen above the ground only when in flower and fruit, it might be expected to be more widespread and should be searched for in appropriate habitats.
Distribution:
S. Malawi, NE. Zimbabwe, WC. Mozambique
Images:
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Botanical Drawing / Herbarium
Gastrodiaballii
Photograph copyright Swiss Orchid Foundation at the Herbarium Jany Renz Image used with kind permission.