JULT, 1912.J 



35 



Edible Products. 



at least pasty. The size of the starch 

 granule does not appear to vary greatly 

 in the different kinds of yams ; it is 

 of moderate size and somewhat resembles 

 the cassava granule. 



The color of the fecnla, or starchy 

 matter of the root, varies from snow 

 white to a dull purplish black ; many 

 varieties are simply tinged wilb reddish 

 or purple, but probably 75 per cent, of 

 the total number are creamy white in- 

 side with an inner bark of some other 

 shade, such as pink, purple, yellow s etc. 

 There is a wide range of aroma in the 

 cooked roots ; one of the common 

 Philippine yams when baked has a 

 pronounced odour like that of fresh 

 raspberries. In 1907 this variety was in- 

 troduced into the United States* by Mr. 

 William S. Lyon and the writer. 



Much has been written about the 

 " air-potato " but this yam deserves very 

 little attention by the practical agri- 

 culturist. Its axillary tubers, some- 

 times weighing up to 500 grams, are so 

 bitter that unless specially treated by 

 lime juice and by soaking in water before 

 cooking they are hardly edible. This 

 species (D. bulbifera) is an exception to 

 the rule that all yams produce edible 

 rootstocks. The potato-like tubers, 

 which are borne in the axils of the 

 leaves, are of an almost indescribable 

 shape,— roughly three-angled, convex on 

 one side, and sometimes with the angles 

 more of less notched or toothed. Some 

 species of yams, like the Hawaiian, may 

 reproduce themselves by small axillary 

 tuberous roots while under certain 

 conditions the " Water " yam group may 

 have a small number of axillaiy tubers, 

 or adventitious tuber-like roots, of very 

 variable seizes and shapes, but always 

 covered with a coarse strong bark like 

 that of the true rootstock. These above- 

 ground tubers and tuberous roots may 

 be used for propagation and are especi- 

 ally usetui in shipping by mail, since 

 they will ordinarily endure four to eight 

 months without moisture. It is a 

 question whether these small resting 

 buds would produce as great yields as 

 would the ordinary root stocks or 

 sections thereof. 



On account of the tendency on the 

 part of the larger growing types of yams 

 to bury the main roots to a depth of 50 

 or even 80 centimeters below the soil 

 surface, it is customary to plant the 

 cuttings, or " root heads "on top of a 

 mound of earth ; this is possible bt cause 

 of the ulter disregard of the young yarn 

 plant for moisture. While every olher 

 plant, except perhaps the cacti, would 

 be dried out before the feeding roots 

 could get down into tlie moist soil, this 

 high-hilling style of planting does no 

 harm to the yams. A system recom- 

 mended for planting the Porto Rico 

 yams and which is believed to be 

 the best for large plants or plantations is 

 the following : A deep trench is made by 

 ploughing, either wiiha middle-br eaker 

 plough or by running an or dinary plough 

 in opposite directions In one furrow and 

 then removing the loore earth in the 

 furrow by means of a spade , this furrow 

 now being 25 to 40 centimeters deep is 

 filled in with layers of grass, weeds, 

 leaves, etc., and earth alternately, each 

 layer being from 10 to 15 centimeters 

 thick. When this operation is completed, 

 all the loose earth on each tide of the 

 trench being brought up, there will be 

 formed a ridge over the trench ; at the 

 time of setting the " heads " this ridge 

 will have settled somewhat and it should 

 then be elevated by taking up the earth 

 on each side until some 8 co 12ceutimeiers 

 of earth are left on top of the heads 

 which should be some 20 to 30 centi- 

 meters above the normal soil surface. 



The heads may be set from 30 to 60 

 centimeters apart in the case of the 

 smaller growing varieties, and 50 to 100 

 centimeters apart in the case of the 

 larger sorts. The trenches, or rather 

 ridges, thuuld be from tiO to 120 centi- 

 meters apart, depending upon the 

 variety, soil, etc. The trench must 

 always be drained since yams are in- 

 tolerant of any staguant water. In case 

 of a sloping surface the trenches should 

 run parallel with the slope, so that no 

 rain water may collect between the 

 ridges. This system greatly facilitates 

 digging the deep-rooting sorts and ap- 

 parently enables the yam root to strike 



