Dioscorea preussii subsp. hylophila (Harms) Wilkin

J. R. Timberlake, E. S. Martins (2009). Flora Zambesiaca, Vol 12 (part 2). Royal Botanic Gardens, Kew

Type

Type Tanzania, W Usambara Mts, Lutindi, ♂ fl., no date, Holst 3423 (B holotype, K).

Morphology General Indumentum

Indumentum usually dense on stem, lower surface of leaf blade and inflorescence

sex Male

Male flowers on pedicel to 2 mm long (single flowers) or peduncle to 3 mm long, pedicel 0.4–1 mm long (cymules); tepals suberect and ventrally concave at anthesis forming a cup-shaped flower, outer whorl dorsally pubescent; 1.3–2.2 0.8–1.8 mm, broadly ovate to orbicular, inner whorl 1.1–2 0.8–2.1 mm, ovate to broadly so. Male inflorescence with flowers in cymules of 2–3(6) flowers, rarely 1 or 2 solitary flowers per inflorescence

Distribution

Zambia, Malawi, Mozambique. Also in Tanzania.

Ecology

In riverine vegetation and open woodland; 300–1700 m.

Phenology

Flowering in January and February; fruiting from February onwards.

Conservation

Conservation notes Widespread taxon; not threatened.

Recognition

D. preussii is easily identified by its unique T-shaped hairs and oblong capsule with a wing along the dehiscence zone. As in D. hirtiflora, the distribution of infraspecific variation suggests that subspecific rank is the most appropriate. If more populations of D. preussii subsp. preussii are discovered in Mozambique, however, there would be grounds for reducing the two subspecies to varietal rank. The single record from Mozambique may be a relict population or a relatively recent dispersal. The females of the two subspecies are indistinguishable in fruit or flower. Wilkin & Tawakali 788 is atypical in that its female flowers have floral bract to 15 mm long, narrowly elliptic to lanceolate or linear and leaf-like in texture.

Use

In Mozambique, the tuber of this subspecies is said to be edible. However, there are also reports that this species is poisonous and that it is used as a cure for snakebite.