Aloes and Lilies of Ethiopia and Eritrea

Habitat and
distribution
Dioscorea
dumetorum
Description
Habitat and
distribution
DIOSCOREA 311
perianth subglobose c. 1 mm long, densely pubescent; stamens 6.
Female inflorescences: pendulous spikes 15–20 cm long, in the
axils of leaves. Capsule 5–7 × 2.5 cm, velutinous, reflexed upwards.
Seeds with a wing on the basal side only.
The species grows in broad­leaved deciduous woodland
with Adansonia digitata and Boswellia papyrifera,
along river valleys between 900 and 1300 m in Tigray
and Gonder floristic regions. It also occurs in Tanzania,
Burundi, Zaire, Zambia, Malawi, and Zimbabwe. The
main flowering period in Ethiopia is from August to
September.
3. Dioscorea dumetorum (Kunth) Pax
The specific epithet ‘dumetorum’ refers to the thicket
(dumetum) habitat in which the plant grows.
The species was described as Helmia dumetorum by
Kunth in 1850 from plants collected in Tigray floristic
region by Schimper. It differs from the related species,
D. cochleari-apiculata by the 3-nerved leaflets and
the glabrous perianth and mature capsule glabrous. In
contrast, D. cochleari-apiculata has 3-nerved leaflets,
and perianth and mature capsule pubescent.
Prickly twiner or climber, stems growing 8–10 m long. Bulbils in
the axils of leaves, prickly, 3–5 cm long, pubescent. Tubers renewed
annually with several per plant; each tuber subglobose or cylindrical.
Leaves alternate, 3­foliolate, pubescent above, tomentose below,
rarely glabrescent; petiole 5–20 cm long, generally prickly; petioles,
0.3–1 cm long; lateral leaflets obovate, 5–16 × 3–15 cm, acute to
acuminate at the apex, cuneate or rounded at the base, conspicuously
3-nerved from just above the base. Male inflorescences: axillary or
terminal, much branched panicles of dense spikes; spikes short,
0.5–1(–1.5) cm long, subsessile or with peduncle up to 0.3 cm
long, cylindrical; bracts broadly ovate, adpressed to the perianth
and partly concealing it, densely pubescent. Male flowers: perianth
subglobose, glabrous, opening little; stamens 6 at least in the first
flowers and 5 or fewer in successive ones. Female inflorescences:
pendulous axillary spikes, 10–20 cm long. Female flowers: directed
downwards, softly tomentose all over; ovary densely pubescent.
Capsules directed upwards, 2.5–4.5 × 1.7–2.4 cm, glabrous to
sparsely pubescent. Seeds with a wing on the basal side only.
The species grows in Combretum-Termi nalia woodland
and secondary thickets, and along river valleys between
900 and 1525 m in Tigray, Gonder, Gojam, and Wellega
floristic regions in Ethiopia and in Eritrea. It is also