Aloes and Lilies of Ethiopia and Eritrea

Dioscorea alata
Description
Habitat and
distribution
Dioscorea cayenensis
DIOSCOREA 315
kunthianurn wood land, disturbed areas on dark­brown
loamy soil or lava, between 1600 and 2000 m, and it is
widespread in Ethiopia. It also grows west to Nigeria
and south to Zimbabwe and Mozambique. The main
flowering period in Ethiopia is from May to June.
7. Dioscorea alata L.
The specific epithet ‘alata’ refers to the winged stems.
The species was described by Linnaeus in 1753 from a
plant collected in Sri Lanka (Ceylon) by Hermann.
It differs from all the related species with simple
leaves by the winged or four­angled stems. In contrast,
the other species have stems that are rounded and without
wings.
Vigorous twiner with stem 10–12 m long, unarmed, glabrous,
4­angled or 4­winged. Some forms bear bulbils. Tuber annual, often
large, varying in size and colour; single or digitate, descending
vertically, branched or recurved as a tusk of an elephant, sometimes
twisted; flesh generally white, sometimes mottled with purple or
wholly purple. Leaves opposite, sometimes the lower alternate or
with 2–4 cataphylls at the base, higher up sometimes in whorls of 3
or 4; petiole 8–10 cm long, winged and decurrent on the stem; blade
ovate to broadly elliptic to deeply cordate, with overlapping lobes
in the basal leaves; 6–22 × 3–18 cm, acute at the apex, subtruncate
to cordate at the base; 5–7(–9) nerved. Male inflorescences: axillary
panicles of several leafless spikes, 15 cm or more long; each spike
with 12–20 sessile alternately arranged flowers on a zigzag axis.
Male flowers: perianth subglobose; outer whorl oval-elliptic, inner
whorl subspathulate; stamens 6. Female inflorescences: solitary
spikes in the axils of leaves, 20–30 cm long, glabrous. Capsule
emarginate, 20–25 × 30–35 mm, glabrous. Seeds suborbicular,
winged all round.
The species is cultivated for its edible tubers at around
1900 m in Illubabor floristic region. It is also cultivated
in most parts of the tropics.
8. Dioscorea cayenensis Lamarck
The specific epithet ‘cayenensis’ refers to the name of the
locality, Cayenne, in French Guyana from where the type
specimen was collected. The species was described by
Lamarck in 1789.