Yam
Dioscorea deltoidea
Family: Dioscoreaceae
What it is like
Dioscorea deltoidea is a PERENNIAL CLIMBER growing to 3 m (9ft 10in). 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 can grow in semi-shade (light woodland) or no shade. It prefers moist soil.
Height (m): 3
Where it is found
Forests and humus-rich soils, 1700 - 2800 metres in Kashmir. Broad-leaved forests and scrub forests at elevations of 2000 - 3100 metres in western China.
E. Asia - Himalayas from Kashmir and Punjab eastwards to Nepal and China.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 2
Tuber - cooked. A slightly bitter flavour, it is usually boiled with some wood ash in order to remove the bitterness. Some caution is advised. See notes below on other uses of the root and above on toxicity.
Root: includes bulbs, corms, tubers, rhizomes etc.
Medicine
Rating: 2
The juice of the root tuber istaken in the evening in the treatment of roundworm. It is also used to alleviate constipation. 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. The roots of this species contain an average of 4.8% diosgenin.
Contraceptive: Prevents fertilization occurring in females.
Miscellany: Various medicinal actions that need more clarification.
Parasiticide: Treats external parasites such as ringworm This should perhaps be joined with Parasiticide in
Other
Rating: 2
A soap is obtained from the tuber. This soap is due to the presence of poisonous saponins in the root. The soap is also used as a body wash to kill lice.
Miscellany: A rag-bag of items that are difficult to categorise.
Parasiticide: Kills external body parasites such as hair lice.
Soap: Plants used directly as a soap substitute.
How it is grown
We have very little information on this species and do not know if it will be hardy in Britain. It is unlikely to succeed in any but the mildest areas. It is cultivated for its edible root in India. The following notes are based on the general needs of the genus. Easily grown in a fertile well-drained soil in a sunny position or light shade. Prefers a rich light soil. Plants produce tubercles (small tubers that are formed in the leaf axils of the stems), and can be propagated by this means. A climbing plant that supports itself by twining around the branches of other plants. Dioecious. Male and female plants must be grown if seed is required.
Propagating it: Seed - sow March to April in a sunny position in a warm greenhouse and only just cover. It germinates in 1 - 3 weeks at 20°c. Prick out the seedlings as soon as they are large enough to handle and grow on in a greenhouse for their first year. Plant out in late spring as the plant comes into new growth. Basal stem cuttings in the summer. Division in the dormant season, never when in growth. The plant will often produce a number of shoots, the top 5 - 10 cm of the root below each shoot can be potted up to form a new plant whilst the lower part of the root can possibly be eaten. Tubercles (baby tubers) are formed in the leaf axils. These are harvested in late summer and early autumn when about the size of a pea and coming away easily from the plant. They should be potted up immediately in individual pots in a greenhouse or cold frame. Plant out in early summer when in active growth.
Best place to grow: Woodland Garden Sunny Edge; Cultivated Beds;
Habit: Perennial Climber
Hardiness:
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: Semi-shade, no shade
Moisture: Moist
Things to keep in mind
Edible species of Dioscorea have opposite leaves whilst poisonous species have alternate leaves.