COOK AND COLLINS—ECONOMIC PLANTS OF PORTO RICO. 185 
have been conducted, on which a report has been made during the past year, and 
as this supplements the information furnished by Mr. Fairchild, and represents 
what is now known about the subject in that island, it seems best to include it 
here: 
The experiments in connection with this class of plants have been continued at 
St. Clair,and the improvement of the quality of the tubers grown in the new 
ground is so marked as to be patent to the veriest novice. 
The kinds grown were as follows: 
Yellow yam __. oo. ; __.. Dioseorea eayenensis. 
White yam . oe Dioscorea alata. 
Negro yam _ - — ao Dioscorea alata, var. 
Red yam __-. _— Dioscorea alata, var. 
Horn yam -_- _. Dioseorea alata, var. 
Water yam - Co : Dioscorea alata, var. 
Chinese yam - - ooo. ___._ Diosecorea batatas. 
Afoo yain __- ____. Dioseorea lutea. 
Cush-cush, or Indian yam - , _Dioscorea trifida, 
Dioscorea bulbifera is so evidently inferior that its culture has not been con- 
tinned. The ‘devil yam,’ which was taken to be a very coarse variety of D. 
alata, has also been discarded as useless. The ‘* negro yam” is by far the best of 
the white yains grown. The‘ yellow yam" is also a good table kind, very sweet 
and wholesome and much liked by Americ an and Eur opean V isitors. 
The * cush-cush,”’ or ‘‘ Indian yam,’ also known as ** yampee.”” gives but very 
small tubers, and there are three or more varieties—red cush-cush, white cush- 
cush, and Demerara cush-cush. The last-mentioned kind has larger tubers than 
the others, testiculate in form, and generally of excellent quality. It has been 
found that the return made by varieties of this species is much less than from 
any other, but it is probably superior to any for the table of the better classes, 
although it would not be profitable to grow where a cheap supply of food stuff 
was r equired, 
The **‘ Chinese yam,’ as I know it, is one of the best. Well grown and well 
ripened, it is of fine quality for table, and probably ¢ ‘omes nearer in flavor to a good 
potato than any other variety. The ‘‘afoo yam’ is the most inferior of all. 
This name, however, 1s sometimes applied to the ** yellow yam,’ so that one may 
get the worst as well as the best yams under the same name, so little is local 
nomenclature to be trusted. 
The yield of yams given in former reports has been more than maintained. 
White yam gave over 20 pounds weight to a plant; Negro yam, 17 pounds; Chi- 
nese yain, 19) pounds; yelow yam, 12 pounds; and cush-cush, 7 pounds. Yams 
grown from aerial tubers, i. e., tubers which develop on the vines, gave 19 pounds 
per root. White yam yielded at the rate of 13 tons to an acre. If 25 per cent is 
deducted from this for waste and for planting again. there is still a crop of 10 tons 
per acre to be registered as the crop for the year of 1898, 
The importance of similar and more extended experiments in Porto Rico is 
obvious, both for the sake of stimulating progress in the direction of mixed farm- 
ing and greater local production of food stuffs, and because it is probable that 
among so many botanical species of different origins special adaptations to soils 
and climates will be found to exist, a knowledge of which will be, of the utmost 
practical importance in utilizing these valuable food plants. The excellence of 
the crop will also determine the possibility of opening a trade with the United 
States, as suggested by Mr. Fairchild. It has been found that properly packed 
yams may be shipped from the West Indies to New York and interior points and 
arrive in good condition. - 
Dioscorea alata. 
This species seems to be one of the commonest in Porto Rico, and may be recog- 
nized by noting that the vine has thin ridges or wings on the stem. 
In Jamaica this species is said to be particularly useful on account of the fact 
that it bears well on shallow or marly soils, while other kinds require deep mold; 
it is also thought to keep better than the other species. 
Dioscorea chondrocarpa. 
A wild yam, growing in forests near Yabucoa.  (Sintenis. ) 
