Dioscorea villosa is a highly polymorphic species, exhibiting complex patterns of variation across its geographic range. Whilst there is a significant degree of genetic variability within the complex, there appears to be no natural gaps in the variation between the plants that sometimes been designated distinct species. Therefore the complex is treated as a single species[].

Common Name: Wild Yam

General Information

Dioscorea villosa is a perennial climbing plant with brownish rhizomes that can vary from unbranched to highly branched and are around 5 - 15mm in diameter. It produces a number of stems up to 7 metres tall[].
The plant is harvested from the wild for local use as a food and medicine.

Known Hazards

Edible species of Dioscorea have opposite leaves whilst poisonous species have alternate leaves[]. Use of the fresh plant can cause vomiting and other side effects[].

Botanical References

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Range

Central and Eastern N. America - Minnesota, southern Ontario and New England, south to Texas and Florida.

Habitat

Borders of bogs, swamps, marshes, river and lake margins, creek bottoms, sandy or rocky soils, moist or dry woods, hammocks, thickets, limestone or talus slopes, roadsides; at elevations from sea level to 1,500 metres[].

Properties

Edibility Rating
Medicinal Rating
Habit	Perennial Climber
Height	3.00 m
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Dioscorea villosa lis a moderately cold-tolerant plant, when fully dormant it can withstand temperatures down to at least -15°c[].
An easily grown plant, succeeding 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[].
This is a highly polymorphic species, some botanists dividing it up into several species[, ].
A dioecious species - both male and female forms must be grown if fruit and seed are required.

Edible Uses

Tuber - cooked[]. Some caution should be exercised with this plant. See 'Medicinal Uses' for more information.

Medicinal

Wild yam roots, and the roots of many other members of the 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 are anti-inflammatory, antispasmodic, cholagogue, diaphoretic and vasodilator[, ]. They are also a visceral relaxant[]. This plant affords one of the best and fastest cures for bilious colic, it is especially helpful in treating the nausea of pregnant women[] and has been used to ease the pain of childbirth[]. The root is also taken internally in the treatment of arthritis, irritable bowel syndrome, gastritis, gall bladder complaints, painful menstruation etc[].
The root is harvested in the autumn and dried for later use[]. The root should not be stored for longer than 1 year, since it is likely to lose its medicinal virtues[].
Caution is advised in the use of the this plant, when taken fresh it can cause vomiting and other side effects[].

The root, harvested in September, is used to make a homeopathic remedy[]. Its main use is in the treatment of infant colic[].

Other Uses

None known

Propagation

Seed - sow early spring to mid spring 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[].