Aerial Yam, Air Potato

Dioscorea bulbifera

Physical Characteristics

Dioscorea bulbifera is an evergreen Perennial Climber growing to 10 m (32ft) by 0.5 m (1ft 8in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 9. The flowers are pollinated by Wind, Insects. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils and can grow in very acid and very alkaline soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil and can tolerate drought.

Distribution

E. Asia - Malaysia.

Habitats

Edible Uses

Edible Parts: Flowers Root Edible Uses: Aerial tubers - cooked[ 300 ]. An agreeable taste, they can be boiled, baked, fried etc[ 301 ]. They must be thoroughly cooked in order to destroy toxic alkaloids[ 300 ]. Wild forms of the plant are always toxic raw, though selected cultivars have been developed that are much lower, or even free from, the toxins[ 332 ]. The tubers are produced, and can be harvested, over a long period of time[ 301 ]. Root - cooked[ 300 ]. Roots are usually around 0.5kg, though they can be up to 1.5kg[ 300 ]. They are not always produced by the plants[ 300 ]. The inflorescences are apparently eaten[ 301 ].

Medicinal Uses

Antidiarrhoeal Antifungal Antihaemorrhoidal Antiinflammatory Antirheumatic Diuretic Febrifuge Ophthalmic Parasiticide Poultice Skin The juice of the roots is taken to expel threadworm[ 272 ]. The juice is dripped into wounds to expel worms and germs[ 272 ]. Both the tuber and the bulbil of wild races have medicinal uses[ 332 ]. In particular they are used externally, usually as a poultice, to treat wounds, sores, boils and inflammations; in dressings for treating dermal parasitic and fungal infections; or crushed, mixed with palm oil, and massaged onto areas of rheumatism, and for troubles of the breasts and for jiggers[ 332 ]. In India the tuber is considered to be diuretic and to be a remedy for diarrhoea and haemorrhoids[ 332 ]. The fruits are used to treat boils and for fever[ 332 ]. Sap expressed from the vine stems is applied to treat purulent ophthalmia, and for snake-bite[ 332 ]. The leaves are used, often by steam-distillation, against pink-eye[ 332 ]. Various medically active substances have been detected in the plant. Dioscorine has been detected in the tuber, though certain Nigerian material has been reported free of the alkaloid[ 332 ]. Alkaloids have been reported from the leaves and stems and particularly in the fruits[ 332 ]. Diosgenin has been detected at 0?45% concentration[ 332 ]. Saponin is present and a number of other pharmacologically active substances[ 332 ].

Known Hazards

Edible species of Dioscorea have opposite leaves whilst poisonous species have alternate leaves[ 174 ]. The aerial bulbs of this species contain toxic substances, including the alkaloid dioscorine[ 300 ]. This can be destroyed by thorough cooking[ 300 ]. Asiatic forms of the plant usually contain less alkaloids than plants originating in Africa[ 300 ]. There are forms that are almost or entirely free of toxins[ 332 ].(Parts of plant are poisonous if ingested)