July, 1912.] 



33 



Edible Products. 



ever been made, either in the Western 

 or Eastern Hemisphere. The writer 

 once grew a collection of about 25 kinds, 

 nearly all of which were of West Indian 

 origin. It is probable that the Pacific 

 archipelago and the East Indies, Philip- 

 pines, India, and Tropical America each 

 possess a considerable number of en- 

 demic varieties and it is quite possible 

 there are 100 distinct forms of the true 

 yams in cultivation at the present day. 



Most yams have peculiar leaves, with 

 3, 5, or 7 midribs instead of one as in 

 mosc other plants. The leaves are fre- 

 quently leathery and shining ; insect 

 pests seem unable to injure them. 



While nearly all the yams are twin- 

 ing or climbing plants, a few, like the 

 "Mapues" varieties of the West Indies, 

 can be grown without artificial supports 

 of any kind. Some varieties attain a 

 height in six months of 20, or even 30 

 metres. A f aw varieties like the " Yam- 

 pee" (Dioscorea trifida) are almost un- 

 branched ; that is, the root sends up two 

 or three stems which grow principally at 

 the tip without producing many side 

 branshes ; others, like the " Water ' 

 yams (D. alata) throw out a vast number 

 of side branches, a single plant being 

 able to cover a surprisingly large area 

 with its luxuriant but weak foliage. 

 Some varieties have strong woody stems 

 which may attain a diameter of 3 or 4 

 centimeters, while others produce only 

 slender herbaceous stems. Many varie- 

 ties are armed with strong prickles, and, 

 in a few cases, even the roots bear such 

 defensive spines that the harvester must 

 remember to never put his hands into 

 the hill in digging out the roots. 



The flower clusters, when produced, 

 are usually a raceme, or spike. The seed 

 from these, in some varieties at least, is 

 winged to enable it to be carried by the 

 wind. The roots sometimes called 

 tubers, but always incorrectly, have no 

 *' eyes " whatever. While filled with a 

 starchy substance like the potato and 

 cassava, they are usually covered with a 

 more or less thick rough bark ; a few of 

 the Philippine varieties are clothed only 

 by a thin integument resembling that of 

 5 



the ordinary potato. In most varieties 

 the root is irregularly cylindrical but 

 may be of almost any shape ; in fact, 

 the shape of the root and the colour of 

 its integuments (for there is a true, usu- 

 ally coloured skin beneath the coarse 

 outer bark) serve to distinguish the 

 closely related varieties which may be 

 apparently identical as to foliage and 

 habits of growth. In India a few kinds 

 (the D. globosa) are nearly spherical. 

 Some kinds produce a dozen or more 

 finger-like, roots, more or less attached at 

 their bases to the foot of each stem. 

 Some, like the Chinese yam, which is 

 said to be native to the Philippines, have 

 very long and slender roots ; this feature 

 renders their cultivation extremely diffi- 

 cult, although their quality may be 

 excellent. One of the wild yams of 

 Porto Rico has roots scarcely evermore 

 than 3 centimeters in diameter, but of 

 indefinite llength ; the quality is so fine, 

 however, that the natives frequently 

 forsake their fields of sweet potatoes, 

 yautias, and even ordinary yams, to dig 

 for this wild inhabitant of the jungle. 



The weight of the edible roots of the 

 yam plant of course varies with the 

 variety, the cultivation given it, and the 

 season, soil, etc. While one-half kilo 

 may be considered a fair yield for the 

 very high-priced " Mapues," and 2 kilos a 

 heavy yield for the delicious " Yampee," 

 some of the "Water " yams may give 10, 

 or even 25 kilos. The world's record for 

 a yam root was probably attained in the 

 State of Florida, ljUnited States of 

 America, a few years ago when one plant 

 gave some 60 kilos of edible root, though 

 this was probably the result of two 

 seasons ' growth. Ordinarily six or eight 

 months suffice to mature roots of the 

 principal cultivated varieties ; a few can 

 reach maturity in five months, while 

 some wild forms require at least twelve, 

 and probably in many cases, twenty or 

 more months to reach their maximum 

 size. 



In planting yam roots only the basal, 

 or upper portion, is customarily used; 

 under favourable conditions even the 

 tip of the yam root can be made to 



