UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1167 
Washington, D. C. T AugusI, 1923 
CULTIVATION OF THE TRUE YAMS IN THE GULF REGION. 
By Roberta. Young. Plant Introducer, Office of Foreign Seed and Plant Intro- 
duction. Bureau of Plant Industry. 
CONTENTS. 
Page. 
What the true yams are 1 
Economic importance of the true 
yams 1 
Opportunity for a yam industry in 
the South 2 
General description of the true yarns- 2 
Kinds of yams 2 
Page. 
The greater, or ten-months, yam 4 
Growing the greater yam 5 
Handling the yam crop 8 
Varieties of the greater yam 10 
Preparation of yams for the table — 13 
Summary 14 
WHAT THE TRUE YAMS ARE. 
The true yams belong to the genus Dioscorea, which includes some 
250 species of climbing vines with underground tubers. The edible 
species of yams produce starchy tubers similar to the white (Irish) 
potato in food value and taste: many varieties are equal or superior 
to the best white potatoes. The name "yam," as used for these 
> plants, should not be confused with the name applied to certain 
moist varieties of sweet potato (Ipomoea batatas). True yams and 
sweet potatoes are unrelated botanically and, although the plants of 
both are vines and produce underground tubers or tuberous roots, 
neither the vines nor the tubers of the two groups bear a real resem- 
blance to each other. 
ECONOMIC IMPORTANCE OF THE TRUE YAMS. 
Not all of the yams produce edible tubers, but of the edible species 
a few are of great economic importance. Yams form a considerable 
part of the food supply of the peoples of many humid tropical 
regions, 1 and they are used to a limited extent outside of the Tropics, 
more especially in China and Japan. It seems remarkable that a 
vegetable of such merit should not long ago have received more 
serious attention from Americans. 
1 Fairchild, David G. Yams in the West Indies, Circular No. 21. Div. of Botany, 1 . B 
Dept. of Agr., 1899. A brief account of yam culture in Jamaica and Barbados. 
45200—23 
