Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

English: Zanzibar yam

Habit:  vine

Description:  "Tuber perennial, becoming very large in age, depressed globose, flattened below, hollowed towards the center, developing roundish lobes in age, up to 40 cm in diameter and 15 cm deep, the upper surface near ground-level.  Plant glabrous.  Twining stems 25 m or more long.  Leaves normally opposite; petiole 8-12 (-26) cm long; blade heart-shaped, up to 20 (-46) cm long (including acumen) and 23 (-58) cm broad, with a thickened acute acumen 5 (-20) cm long; towards base of stem leaves replaced by fleshy auricles; leaf-blades of young plants variously shaped and lobed.  Aerial tubers irregularly roundish, up to 6 cm diameter, deep purplish.  Inflorescences pendulous, spicate.  Male 1 or 2 per leaf-axil or forming a terminal leafless panicle; spikes up to 50 cm long, with 1 or 2 downwardly directed flowers at each node, not opening wide, ± 5 mm long.  Stamens 6.  Female inflorescences 1-3 per leaf-axil, up to 48 cm long; flowers solitary at a node, directed downwards; perianth not opening wide, 177; 3 mm in diameter.  Ovary ± 6 mm long.  Capsule ± 5 cm long and 2.5 cm in diameter, directed upwards.  Seeds winged at both ends, ± 3.5 cm long" (Milne-Redhead, 1975; pp. 7-9).

Habitat/ecology:  In east Africa, "Lowland rain-forest, riverine forest, Acacia woodland, coastal evergreen bushland; often persisting in secondary vegetation; 0-900 m" (Milne-Redhead, 1975; pp. 7-9).

Propagation:  Seed

Native range:  "Ivory coast to the Sudan, south to Angola, Rhodesia and Mozambique, also in Madagascar" (Milne-Redhead, 1975; pp. 7-9).

Presence:

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Singapore Singapore	Singapore (Republic of)		Rejmánek, M. (1996)
Singapore Singapore	Singapore (Republic of)	introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 34) Naturalised

Comments:  Reported to be an invasive species in Singapore per Rejmánek, 1996.

Control:  Control information from the Bugwood Wiki.

Additional information:
Information from the Bugwood Wiki.

Additional online information about Dioscorea sansibarensis is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Dioscorea sansibarensis as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Dioscorea sansibarensis may be available from the Germplasm Resources Information Network (GRIN).

References:

Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. 2009. A checklist of the total vascular plant flora of Singapore: native, naturalised and cultivated species. Raffles Museum of Biodiversity Research, National University of Singapore. 273 pp.

Milne-Redhead, E. 1975. Dioscoreaceae. In: Polhill, R. M., ed. Flora of tropical east Africa. Crown Agents, London.

Rejmánek, M. 1996. Species richness and resistance to invasions. In: Orians, G., R. Dirzo and J. H. Cushman (eds.). Biodiversity and ecosystem processes in tropical forests. Springer-Verlag. pp. 153-172.

U. S. Government. 2011. Integrated Taxonomic Information System (ITIS) (on-line resource).