788 
Supplement to the " Tropical Agrimltxmst." 
[May 1, 1900. 
THE CULTIVATION OF YAMS. 
It; cannot be denied that the caUivatioti of 
yams is not sufficiently carried on in Ceylon, and 
that the product is not sufficiently made use of for 
food purposes. ladeed, such cultivation as we 
hftve is on the most limited scale, and only unsyste- 
matically carried on. In the West Indies on 
the other hand th» yam is a regularly grown 
crop and duly appreciated as a food product- 
lu Ceylon we are accustomed to hear the word 
"yam "applied indiscriminately to the produce 
both of true yam plants, members of the natural 
order Dioscoraceae and that of theColocasias which 
belong the order Araceae. But in the West Indies 
the name is confined to the former only, while 
the word "tania" is used to distinguish the 
produce of the Colocasias. 
The following account of yam cultivation in 
the West Indies by Dr. Alford NichoUs is 
worthy of reproduction, as containing many valu- 
able hints which should prove useful to local 
cultivators. 
Yams are the esculent tubers of several species 
of Dioscorea that have been cultivated in warm 
countries for ages. More nutritious than the 
common potato, they supply an abundance of 
wholesome food to the inhabitants of tropical and 
sub-tropical regions ; and, in the West Indies 
they enter very largely into the diet of all classes 
of the population. 
Most of the cultivated varieties of yams are pro- 
bably natives of tropical Asia, that have been 
introduced into the West Indies at an early period 
of their colonisation by Europeans, and now become 
almost wild. The only yam of good flavour and 
food value, that naturally belongs to the flora of 
the West Indies, is the " Wawwaw" of Dominica, 
Jtajania pleioneura, which grows abundantly in 
the forests of that Island. It is dug up by the 
woodmen and sold in the markets of the chief 
town, for it is deservedly held in much estimation. 
After the hurricane of 1883, when most of the 
provision grouiid.s in Dominica were laid wnste, 
many of the country people subsisted for weeks 
almost entirely on wawwtiws, dug up in the 
forests. All the yums are the pro<luce of plants 
with slender twining stems measuring often as 
much as twenty feet in height, and bearing under- 
ground tubers which spring from the principal 
roots. The tubers vary in size and weight from 
the small cush-cush no larger than ordinary 
potato to the enormons yam weighing thirty or 
forty pounds, and measuring three feet in length. 
There is confusion in regard to the names and 
characters of the different yams, each country 
appearing to have its own nomenclature. There 
are four kinds of yams, however, commonly culti- 
vated in the West Indies, imu the mobt noticeable 
particulars concerning them are as follows : — 
White Yam {Dioscorea Alata). — This is some- 
times called tlin Barbadris yam, is a native of the 
Mriluccas and Java. The stem is square and 
winged lit each angle. The leaves are laige, 
heurt-sliaped and opposite on the stem. A pecu- 
liarity of this plant is that bulbils or small yjims 
are borne on th« stem, and when they are ripe 
they fall to the ground and reproduce the species. 
Tho tuberi are larg« weighing from eight to ten 
pounds when grown in good soil. There are two 
principal kinds, the white and the red, the surface 
of the latter is of a deep purplish, and the 
interior of the tuber of a light purplish colour. 
A third kind called the water yam is characterised 
by the interior of the tuber being of a moist and 
clammy nature. These yams will keep well out 
of the ground, and they are much liked on account 
of their digestibility and their superior flavour. 
Negro Yam (Dioscorea Satiua). — This is some- 
times called the yellow, Creole, or common yam, and 
it is a native of Java and the Philippine Island?. 
The stem, which grows to a length of fifteen or 
twenty feet, is round, prickly below and smooth 
above. The leaves are heart-shaped and alternate 
on the stem. The tubers grow to a large size 
weighing usually about ten pounds ; they are 
palmated in shape and they are so brittle as to be 
easily broken. They are of a white or yellowish 
colour within, but the white kind is liked best. 
These yams do not keep in good condition for 
any length of time after their removal from the 
ground. 
Guinea Yam (Dioscorea Aculeata). — In Jamaica 
this is sometimes called the Afou yam. It is 
largely cultivated throughout the West Indiep, 
but its native country is Cochin China, and it 
comes also from Malabar. The stem is round, 
prickly and much branched. The leaves are 
broadly heartshaped, and either alternate or 
opposite on the stem. The tubers are very large, 
reaching a length of two or three feet, a diameter 
of six or eight inches, and a weight of from 
fifteen to twenty pounds. The interior is of a 
white or yellow colour, and when cooked the 
flavour is somewhat bitter. 
CusH-cuSH Yam {Dioscorea Triphylla). — In 
Jamaica this is sometimes called the Indian yam; 
and in Guiana it is known as the Buck yam. 
The stem is roundish, the leaves are opposite on 
the stem and divided into three leaflets. The 
tubers are roundish — indeed, something like a 
potato in shape. They rarely exceed nine inches 
in length and three inches iu diameter, but they 
are uaually much smaller. It is said to bo the 
smnllest and most delicate of all the yams. The 
phint is prolific, sometimes bearing a dozen tubers 
on the roots. There are two principal kinds, the 
white and red, the latter bearing tubers that are 
purplish within. 
Soil and climatji — All the yams require a 
rich sandy loam, deep and friable, for the rich 
tubers will not be able to develop properly in 
stiff heavy soils. The white yam, however, will 
grow well on calcarious soils of moderate depth. 
Good drainage is necessary, and this applius to 
most plants bearing underground tubers. The 
climate must be warm but not necessarily liot. 
as the plant thrives in the mountains and in excra- 
tropical regioiis. One. authoiiiy states that vams 
will grow withiu a wide zone extending thirty 
degrees north and south of the equator. 
Cultivation. — Most of the yams are propagated 
in the foUnwiiig way ; — When the tubers are ready 
to be dug u]., 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 
