The New International Encyclopædia/Yam
YAM (from Sp. ñame, iñame, igname, ignama, Port. inhame, yam, from African nyame, yam), Dioscorea. A genus of mostly East and West Indian plants of the natural order Dioscoreaceæ, distinguished by an inferior ovary and membranous winged fruit. They have herbaceous twining stems, and fleshy roots which in some species are used as food, like potatoes. They contain much starch, and generally become somewhat mealy and pleasant to the taste when boiled. The tubers of all the yams contain an acrid substance, which, however, is dissipated by boiling, except in the species with compound leaves. The winged yam (Dioscorea alata) has roots 1½ to 3 feet long, and often 30 pounds in weight, with a brownish or black skin, juicy and reddish within. They vary exceedingly in form. Small tubers are generally found in the axils of the leaves. This species is the original of most, or perhaps all, of the yams cultivated in tropical Asia, Africa, and America: the common yam of the West Indies (Dioscorea sativa) , which has a round stem and heart-shaped leaves; Dioscorea bulbifera, in which the tubers in the axils of the leaves attain the size of apples; the prickly yam (Dioscorea aculeata), which has a prickly stem, and a fasciculated, tuberous root; Dioscorea globosa, the most esteemed yam of India, which has very fragTant flowers, and roots white internally; Dioscorea rubella, another Indian kind, with tubers sometimes 3 feet long, tinged with red below the skin, etc. The Chinese yam (Dioscorea divaricata) is a perfectly hardy sort. Its edible club-shaped roots descend perpendicularly into the ground from two to three feet, and largely on this account it is little cultivated.
YAM, SWEET POTATO, ETC.
|1. YAM (Dioscorea alata).||3. OKRA (Hibiscus esculentus).|
|2. ASPARAGUS (Asparagus officinalis).||4. SPINACH (Spinacia oleracea).|
|5 and 6. SWEET POTATO (Ipomœa Batatas).|