Glutinous Yam, Japanese yam

Dioscorea japonica

Physical Characteristics

Dioscorea japonica is a PERENNIAL CLIMBER growing to 3 m (9ft 10in). See above for USDA hardiness. It is hardy to UK zone 8. It is in flower from September to October. The species is dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required).. The plant is not self-fertile. 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. It cannot grow in the shade. It prefers moist soil.

Distribution

E. Asia - China, C. and S. Japan.

Habitats

Woodland Garden Sunny Edge; Cultivated Beds;

Edible Uses

Edible Parts: Leaves Root Edible Uses: Tuber - cooked[174, 177, 179]. A very pleasant mild flavour with a floury texture, the roots can be eaten as a potato substitute[2]. The starch can be used as a binding agent for other foods[183]. Roots contain about 1.9% protein, 20% carbohydrate, 0.1% fat and 1% ash[179]. Leaf tips - cooked[183]. Tubercles - cooked[183].

Medicinal Uses

Contraceptive Miscellany Tonic The tubers are prescribed in the treatment of diarrhoea, enteritis, enuresis and spermatorrhoea. They are also dried and cut into shavings then used as a tonic. The roots of most, if not all, members of this genus, contains diosgenin. This is widely used in modern medicine in order to manufacture progesterone and other steroid drugs. These are used as contraceptives and in the treatment of various disorders of the genitary organs as well as in a host of other diseases such as asthma and arthritis.

Known Hazards

Edible species of Dioscorea have opposite leaves whilst poisonous species have alternate leaves[174].