Yam is the
common name for some species in the genus
Dioscorea (family Dioscoreaceae). These are
perennial herbaceous vines cultivated for
the consumption of their starchy tubers in
Africa, Asia, Latin America and Oceania.
There are many of cultivars of yam.
The sweet potato (Ipomoea batatas) has
traditionally been referred to as a "yam" in
parts of the southern United States and
Canada, but it is not part of the
Although it is unclear which came first, the
word yam is related to Portuguese inhame or
Spanish ņame, which both ultimately derive
from the Wolof word nyam, meaning "to
sample" or "taste"; in other African
languages it can also mean "to eat", e.g.
yamyam and nyama in Hausa.
A Nigerian word for yam is adamwanga,
meaning "Adamo's food". Adamo was a chief
notorious for his ability to consume
incredible amounts of food, and was even
banned from a neighboring village for his
refusal to stop.
Yam tubers can grow up to 2.5 meters in
length and weigh up to 70 kg (150 pounds).
The vegetable has a rough skin which is
difficult to peel, but which softens after
heating. The skins vary in color from dark
brown to light pink.
The majority of the vegetable is composed of
a much softer substance known as the "meat".
This substance ranges in color from white or
yellow to purple or pink in ripe yams.
Yams are a primary agricultural commodity in
West Africa and New Guinea. They were first
cultivated in Africa and Asia about 8000
B.C. Due to their abundance
and consequently, their importance to
survival, the yam was highly regarded in
Nigerian ceremonial culture and even
Yams are still important for survival in
these regions. The tubers can be stored up
to six months without refrigeration, which
makes them a valuable resource for the
yearly period of food scarcity at the
beginning of the wet season.
Yams are used as food plants by the larvae
of some Lepidoptera species including
Higher humilities, at which most other vegetables keep best in
storage, may cause onions to grow roots, rot, and develop
surface mold. Excessive drying, however, may result in cracking
or loss (bald onions) of the outer bulb scales.