XV THE YAM 287 



depth. Good drainage is necessary, and this applies to 

 most plants bearing underground tubers. The climate must Climate. 

 be warm, but not necessarily hot, as the plant thrives in the 

 mountains and in extra-tropical regions. One authority 

 states that yams will grow within a wide zone extending 

 thirty degrees north and south of the equator. 



Cultivation. — Most of the yams are propagated in the Propaga- 

 following way : When the tubers are ready to be dug up, 

 the tops are cut off with the vines attached and care is taken 

 not to disturb the plant more than is really necessary. The 

 top is then buried again in the ground, and it and the base 

 of the vine is moulded up with good soil, and left 

 undisturbed for about three months, when another yam, 

 called the head^ is produced. Plants are then made by Yam plants, 

 cutting the head into pieces, care being taken that each 

 cutting possesses an eye, or bud, from which the new plant 

 develops. 



The land is usually lined out at distances of two feet each Distances, 

 way, or in rows three feet apart, the plants being set at 

 distances of eighteen feet in the rows. At the site of Hills, 

 the pickets the land is dug up, all stones and roots being 

 removed, and the surrounding soil is then raked up so as to 

 form small hills in which the yam plant is set several inches 

 below the surface. In each hill, a stout stick eight feet long Supports, 

 is simply fixed at the side of the plant so as to form a 

 support for the vine to climb on. Sometimes two plants are 

 set in each hill. The land must be kept weeded, and an Moulding 

 occasional moulding up may be necessary, as the heavy ^^^ p'^"'^' 

 rains tend to wash down the hills. Catch crops of maize, 

 and sweet potatoes are sometimes taken off the land between 

 the rows, but this system is a bad one except in very rich 

 soil. From January to April is the best planting season, 

 and the yams require from nine to eleven months to mature. Yams may 

 Planting, may, however, be undertaken in every month of the afi fhe^year 

 year, so as to ensure a constant supply of the esculent tubers. ■■°""^- 



