261. _YAMS are an American and West Indian root of very irregular shape,
which possess properties somewhat similar to those of the potatoe, but
they are less mealy, and, in a raw state, are very viscous._
_The plants_ (Dioscorea bulbifera) _which produce these roots have
heart-shaped leaves, and a stem that creeps along the ground like ivy._
In some of the rich lands of South America, yams are said to grow to the
weight of fifty or sixty pounds each; and are so productive that an acre of
ground planted with them has been known to produce roots to the weight of
from 20,000 to 30,000 pounds. Yams are propagated by setting the eyes, in
the same manner as we plant potatoes; and, in six or eight months, they
arrive at maturity.
When they are dug out of the ground, they are, for a little while, exposed
to the sun to dry; and if, after this, they be packed in casks full of dry
sand, they may be preserved, without injury, for many months. They are
consequently often used as sea-store for vessels about to sail on long
voyages, and are frequently brought into England. Several attempts have
been made to cultivate yams in this island; and these have been attended
with a certain degree of success in the counties of Mid-Lothian, Perth, and
Stirling in Scotland, where they are used for the feeding of cattle. There
are two kinds, one red, and the other white. The former of these contain a
more nutritive food than the latter, though their flavour is much less
excellent.
With the negroes, in the West Indian islands, the yam is a very important
article of food. When roasted, it is so wholesome and nutritive that it is
preferred by them even to bread. Like potatoes, yams may be converted into
bread, by mixture with a portion of wheat or barley flour. They are
sometimes made into soup, puddings, and other useful dishes.