Dioscorea villosa Wild Yam
Researcher: Tanner Filyaw
Common Names:
Colic root
Devils Bones
Rheumatism root
Wilde Yamwurzel (17)
Bitter Yam
Barbasco
Yuma
Liver Root (12)
Four leaf yam (13)
China Root
Atlantic Yam
Wild Gum Root
Huang Yao Tzu
Shu Yu [Raintree] (8)
Genus: Dioscorea (11)
Family: Dioscoreaceae , 29species,
2 genera (11)
Synonyms:
Dioscorea paniculata (Michx.) (14)
Dioscorea hirticaulis ( Bartlett ) (11)
Dioscorea cliffortiana Lam. (1789)|
Dioscorea glauca Muhl. ex Bartlett
(1910)
Dioscorea hexaphylla Raf. (1837)
Dioscorea lloydiana E.H.L.Krause
(1914) (13)
Relatives: There are around 150
varieties of yam (15), with the most
common relatives being Dioscorea
batatas (17), and
Dioscorea quaternata (16).
Duration: Perennial
Habit: Twining herbaceous vine (6).
Height: Average height between 9
and 15 ft. (16).
Stems: Stems are smooth, and
reddish/brown in color (17).
Leaves
http://www.organicnutrition.co.
uk/images/wild-yam.jpg
Leaves:
Leaf arrangement and shape can both
vary with D. villosa . The leaves can
either be alternate or whorled, with
cordate (heart shape) leaves at the base
of the plant and ovate (oval) shaped
leaves near the top (16). The leaf blade
is roughly 2-6 inches long and 1-4
inches wide, with 7-11 parallel
veins (17).
*Note: Edible varieties of wild yam
are known to have opposite leaves,
while poisonous varieties tend to have alternate leaves (18).
Infloresence
© 2002 Steve Baskauf
http://bioimages.cas.vanderbilt.edu/
Flowers:
Wild yam has both male and female
flowers that occur on the same plant.
Flowers are small and greenish
to yellow in color, and bloom from
June to August.
The inflorescences emerge from the
axil of the leaves,with male flowers
occurring in drooping clusters
between 3 and 6 inches long,
and female flowers occurring in
spike-like heads (17).
Fruit
http://www.swsbm.com/Images/
D-G/Dioscorea_villosa-2.jpg
Fruit:
The fruit of D. villosa is a yellow/green
three valve capsule containing two or
more winged seeds. The fruit will ripen
in September and will persist on the
vine for most of the winter months (14).
Root
http://www.herbs2000.com/images/
herbs_wild_yam.jpg
Roots: Wild Yam roots are long, branched, crooked, and form a light browntuber (17).
The root is white on the inside,
measures 1/4-1/2 inch in diameter
(14), and is odorless (5).
Research indicates that environmental
conditions can drastically affect the
growth and development of the roots.
The results show that tubers grown at lower elevations will be greater in size
than those grown at higher
elevations (3).
Seed:
Little is known about the seed biology
of D. villosa, but researchers have
recently begun to shed some light on
its biological characteristics. The seeds
are flat in shape (9), winged, and are dispersed by wind (1). The seeds are considered morphologically dormant
due to a functionally underdeveloped embryo, and require a period of cold stratification prior to germination.
Research indicates, that prior to
germination, the embryos must
develop to a certain threshold before
germination can take place (1).
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Pollination: It is hypothesized that Wild Yam does not self-pollinate (18), and that nocturnal insects are most likely responsible for pollen transfer between individuals and populations (1).
Habitat:
Dioscorea villosa prefers mixed hardwood forest habitats with sandy to clayloam soils that have pH values between 5 and 6 (17). This species can tolerate a variety of conditions, including high light environments (8), and can be found growing along roadsides (17). Research indicates that D. villosa exhibits better growth and development at higher elevations, and that plants grown under these conditions tend to have higher concentrations of the medicinally active constituent diosgenin (3).
Associations:
Canopy:
White oak - ( Quercus alba )
Black oak - ( Q. velutina )
Red and Burr oaks - ( Q. borealis and Q. macrocarpa )
Black cherry - ( Prunus serotina )
Sugar maple - ( Acer saccharum )
Eastern hemlock - ( Tsuga canadensis )
White pine - ( Pinus strobus )
Beech - ( Fagus grandifolia )
Yellow birch - ( Betula allegheniensis )
Basswood - ( Tilia americana )
Understory :
Spring-beauty - ( Claytonia spp. )
Trout-lilies - ( Erythronium spp. )
Trillium - ( Trillium macrophyllum )
Violets - ( Viola spp. )
Bloodroot - ( Sanguinaria canadensis )
Blue cohosh - ( Caulophyllum
thalictroides )
Mayapple - ( Podophyllum peltatum ) (19)
Black Cohosh - ( Actea racemosa ) (16)
Range: New England to Minnesota and Ontario , south to Virginiaand Texas (18).
Native –Dioscorea villosa is the only wild species of the yam family native to the
United States . Most other members of the family are found in South and Central
America . (7).
Pests/diseases: Leaf spots (16)
Other threats: Declining wild populations due to over harvesting.
Conservation status –Cultivation is being promoted as a means to augment existing populations, and establish new populations (1).
History/culture: Due to their large, starchy tubers, domesticated species of yam have been one of the most important staple crops through out much of Africa , Asia , and SouthAmerica (2). Wild species like D. villosa , are not considered important food crops, but have long been recognized as medicinally valuable plants. There have been documented accounts from ancient Aztec and Mayan civilizations that describe the use of wild yam for treating several ailments, and feminine problems (17). Native North Americans also used decoctions of the roots to relieve the pains of child birth and cramping, giving rise to the common name colic root. During the early 19 th century, physicians used this species as an anti-spasmodic more than a pain reliever, and discovered its steroidal properties (7).
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