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Dioscorea sansibarensis Pax
| Family Name: | Dioscoreaceae |
| Synonyms: | Dioscorea macabiha Jum. & H.Perrier, Dioscorea macronra Harms, Dioscorea toxicaria Bojer, Dioscorea welsitschii Rendle. |
| Common Name: | Zanzibar Yam |
Dioscorea sansibarensis, or commonly known as Zanzibar Yam, is a robust, fast-growing climber that can grow up to 25 m or more in height. The vine grows from underground stems called tubers and produces bat-like leaves. Although native to Tropical Africa and Madagascar, it is naturalised in Singapore, where it can be found in our rainforests and along paths and roads.
Name
Classifications and Characteristics
| Plant Division | Angiosperms (Flowering Seed Plants) (Monocotyledon) |
|---|---|
| Plant Growth Form | Climber |
| Lifespan (in Singapore) | Perennial |
| Mode of Nutrition | Autotrophic |
Biogeography
| Native Distribution | Guinea, Ivory Coast, Togo, Benin, Nigeria, Gulf of Guinea Islands, Cameroon, Central African Republic, South Sudan, Equatorial New Guinea, Gabon, Congo, DR Congo, Uganda, Kenya, Tanzania, Angola, Zambia, Zimbabwe, Malawi, Mozambique, Comoros & Madagascar |
|---|---|
| Native Habitat | Terrestrial (Secondary Rainforest, Riverine) |
| Preferred Climate Zone | Tropical |
| Local Conservation Status | Non-native (Spontaneous (Naturalised)) |
Description and Ethnobotany
| Growth Form | It is a robust, fast-growing, perennial, herbaceous climber that can reach 25 m or more in height. It has a twining growth habit. |
|---|---|
| Foliage | The leaves are heart-shaped or "bat-shaped", measuring 6–27 cm long × 7–42 cm wide, including the driptip, with 7–11 prominent veins. The driptip is darker in colour and contains nitrogen-fixing bacteria. The leaves are thin, herbaceous, and have entire, inrolled leaf margins. Leaves on immature vines are much smaller, thinner and variously shaped and lobed. The petioles (leaf stalks) are long (8–12 cm in length) and smooth. The leaves are arranged alternately near the base, then become opposite. Fleshy auricles (ear-like lobes) are present at the nodes, especially near the base of the stem. |
| Stems | The stems are herbaceous and smooth. The stems climb by twining anti-clockwise up tree trunks or vertical supports. |
| Flowers | The inflorescence is a pendulous spike, occurring 1–2 per leaf axil for male inflorescences (up to 50 cm in length) or 1–3 per leaf axil for female inflorescences (up to 48 cm in length). Male flowers occur singly or in pairs, while female flowers are borne singly and directed downwards. The flower is imperfect, having six small tepals (indistinguishable petals and sepals that resemble one another) with floral bracts, and either male or female reproductive organs. The species is dioecious, meaning male and female inflorescences are found on separate plants. Flowering is rarely observed in Singapore. |
| Fruit | The fruit is a winged, bluish-green capsule (a type of dry, dehiscent capsule), measuring 36–50 mm long × 20–28 mm wide. The seeds are winged, measuring about 35 mm in diameter. |
| Reproductive Parts - non-flowering plant | It produces underground globose tubers (up to 40 cm across) that are flattened below and hollowed towards the centre, developing lobes with age. The tubers can be found deep underground or, often, near the ground surface. Bulbils are black (dark-purplish brown when dry) or pale brown and borne at the leaf axils along the stems, reaching about 5.5 cm in diameter. |
| Habitat | It can be found in lowland rainforest, riverine forest, Acacia woodland, and coastal evergreen bushland at elevations of 0–900 m above sea level, often persisting in secondary vegetation. It has been naturalised in Singapore, growing in primary and secondary forests and along paths, roads and clearings. |
| Cultivation | It can be propagated from division and tubers. |
| Etymology | The genus Dioscorea is named after Dioscorides Pedanios of Anazarbeus, a 1st Century Greek physician and herbalist who was the author of 'Materia Medica'. The specific epithet sansibarensis means "from Zanzibar," although the species was first found near Bagamoyo, Tanzania, across from Zanzibar on the mainland. |
| Ethnobotanical Uses | Medicinal: Traditional Medicinal Use In Tanzania, the leaf-sap and root-decoction are drank for epilepsy <1>. It is important to note that some therapeutic effects from traditional medicinal uses of plants are not currently supported or verified by scientific research. Agriculture - Forestry: This species is often planted at the edge of yam (Dioscorea alata) fields in hopes that thieves would steal their tubers instead of the valuable yams <1>. Cultural / Religious: In Dahomey, Benin, it is planted around sorghum granaries as an act of superstition. Others: In its native range, the tubers are considered famine food; they are cut up, boiled, and washed before being eaten <1>. The tubers and bulbils are also used to poison wild animals, or as a fish poison <1>, and in Madagascar, they are used as an ordeal poison <1>. |
Landscaping Features
| Landscaping | Due to its fast plant growth, this species is not recommended for landscaping use. |
|---|---|
| Usage Hazard - Cons | Invasive / Potentially Invasive, Toxic Upon Ingestion |
| Usage Hazard - Cons Remarks | Invasive/Potentially Invasive: The plant produces aerial bulbils that may detach and readily grow as new plants. Toxic Upon Ingestion: All plant parts contain neurotoxic alkaloids, dioscorine and dioscoricine, which can cause throat discomfort, giddiness, nausea, vomiting and sleepiness when consumed. Keep plants out of reach of children and pets. |
Plant Care and Propagation
| Light Preference | Semi-Shade, Full Sun |
|---|---|
| Water Preference | Moderate Water |
| Plant Growth Rate | Fast |
| Rootzone Tolerance | Fertile Loamy Soils |
| Propagation Method | Aerial Bulbil, Division, Storage Organ (Stem Tuber) |
Foliar
| Foliage Retention | Evergreen |
|---|---|
| Mature Foliage Colour(s) | Green |
| Mature Foliage Texture(s) | Raised / Sunken Veins, Thin, Smooth |
| Foliar Type | Simple / Unifoliate |
| Foliar Arrangement Along Stem | Opposite, Alternate |
| Foliar Attachment to Stem | Petiolate |
| Foliar Shape(s) | Non-Palm Foliage (Cordate) |
| Foliar Venation | Pinnate / Net |
| Foliar Margin | Entire |
| Foliar Apex - Tip | Acuminate |
Non - Foliar and Storage
| Root Type | Underground (Fibrous Root) |
|---|---|
| Specialised Storage Organ(s) | Underground (Stem Tuber) |
Floral (Angiosperm)
| Flower & Plant Sexuality | Unisexual Flowers , Dioecious |
| Flower Grouping | Cluster / Inflorescence |
|---|
| Flower Location | Axillary |
| Flower Symmetry | Radial |
| Individual Flower Shape | Campaulate / Bell-shaped |
| Inflorescence Type | Spikelet / Pseudospikelet / Compound Spike, Spike |
| Ovary Position | Inferior / Epipgynous |
| Flowering Habit | Polycarpic |
Fruit, Seed and Spore
| Mature Fruit Colour(s) | Green - Bluish Green |
|---|---|
| Fruit Classification | Simple Fruit |
| Fruit Type | Dehiscent Dry Fruit , Capsule |
| Seed Quantity Per Fruit | Few (1-5) |
References
| References | <1> Burkill, H. M. (1985). The useful plants of West Tropical Africa (2nd ed., Vol. 1: Families A–D). Royal Botanic Gardens, Kew. (Accessed on 02 March 2026) <2> Dioscorea sansibarensis Pax. Flora of Zimbabwe. https://www.zimbabweflora.co.zw/speciesdata/species.php?species_id=115440#:~:text=Notes:,forest%2C%20often%20close%20to%20water. (Accessed on 02 March 2026) <3> Milne-Redhead, E. (1961). Flora of Tropical East Africa: Dioscoreaceae. Royal Botanic Gardens, Kew. (Accessed on 02 March 2026) |
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Image Repository
Others
| Master ID | 88 |
|---|---|
| Species ID | 1384 |
| Flora Disclaimer | The information in this website has been compiled from reliable sources, such as reference works on medicinal plants. It is not a substitute for medical advice or treatment and NParks does not purport to provide any medical advice. Readers should always consult his/her physician before using or consuming a plant for medicinal purposes. |
