9, BULLETIN 1247, U. S. DEPARTMENT OF AGRICULTURE 
with other good taros and with promising yautias. Like the jack- 
in-the-pulpit and the calla, also of the aroid family, nearly all of 
these plants have very acrid leaves. The uncooked corms and lateral 
tubers (cormels) of most varieties are also acrid, though some are 
practically free from this principle.* ; 
USES. 
‘Different species and varieties of the edible aroids vary consider- 
ably in the water content and otherwise in the chemical composition 
of their corms and tubers. In general, they are comparable to the 
potato as food, though most of the more desirable sorts contain less 
water than the driest white potatoes and have a correspondingly 
higher proportion of nutritive materials. They are considered to be 
very easy to digest, and in Hawaii taro in a form called “ poi,” be- 
sides being a common article of food, is often prescribed for invalids. 
The methods of cooking taros and yautias are usually much the same 
as those used for potatoes. In some varieties the corms only are com- 
monly used for food; in many only the lateral tubers are eaten, while 
in many others both corms and tubers are used. | 
In addition to the corms and tubers the young leaves and the leaf- 
stalks (petioles) of the taros and yautias are cooked and eaten, but 
because of their acridity they require preliminary boiling for a few 
minutes with sodium bicarbonate (baking soda).* Cooking them 
also with fat meat without parboiling with soda will usually destroy 
the acridity ; but when cooked by either method the greens should be 
tasted by the cook or housewife before being placed on the table, to 
be sure that they are properly and sufficiently cooked. Young leaves 
not yet open are usually to be preferred for greens, but while the 
plants are growing rapidly even the fully expanded ones are suitable. 
The stalks even of older leaves may be used satisfactorily, especially 
if the skin is peeled off. The same method of cooking as for the leaf 
blades is employed. 
In parts of the world where flowering varieties of taros are grown, 
the flowers also are sometimes cooked and eaten. They are cooked 
by the method used for the leaves. 
RELATIONSHIP OF THE TAROS AND YAUTIAS. 
The taros, of which there are several species, belong to the genus 
Colocasia. The yautias belong to the genus Xanthosoma and in- 
clude a considerable number of species, though only a few are eco- 
nomically important. The botany of these genera has been in a some- 
what confused state, and for some of the varieties discussed here no 
attempt is made to use specific names. Following is a key to the 
vegetative characters, which it is believed will be useful in separating 
the principal varieties of taros and yautias described in this bulletin. 
8 The cause of the acridity of the aroids, which was long in dispute, seems to have been 
definitely determined by a series of experiments by Mr. Black, of the Bureau of Plant 
Industry, to be the raphides, or needlelike crystals, of calcium oxalate which occur in 
bundles in many of the cells of the plant. See Black, O. F., Calcium oxalate in the 
dasheen, Jn Amer. Jour. Bot., v. 5, p. 447-451. 1918. 
*Interested persons are referred to Farmers’ Bulletin 1396 for more detailed directiens 
for cooking the greens, 
