AMERICAN VARIETIES OF SWEET POTATOES. 
mine to which of the three groups a given specimen belongs and then 
to read the descriptions of varieties until one is found which fits the 
specimen. This is a tedious and cumbersome method, although great 
credit is due the originator of this system, for it introduced some 
order into the previous chaotic condition. It is not possible, however, 
to identify many varieties without taking into consideration many 
points other than the shape of the foliage. The description given to 
the varieties is not sufficient to identify most varieties now grown. 
Another classification of sweet-potato varieties that has been pub- 
lished is the one worked out by ( J roth (26) . In this system the follow- 
ing factors are considered in making the key : 
O. Color of lower surface of veins. 
(1) Vein purple. 
(2) Midrib pinkish in some old 
leaves. 
(3) Purple spot at base of mid- 
rib. 
A. Shape of leaf. 
(i) Cut. 
(2) Round. 
(3) Long. 
(4) Broad. 
(5) Mixed (round and lobed). 
B. Size of leaf. 
(1) Small (less than 4 inches 
across). 
(2) Large (more than 4 inches 
across ) . 
V. Length of stem. 
(1) Long (more than 4 feet 
long). 
(2) Short (less than 4 feet 
long). 
D. Color of stem. 
(1) Green (with or without 
brownish areas) . 
(2) Green (with purple around 
the axils of the leaves). 
(3) Greenish brown to purple. 
(4) Purple. 
E. Size of stem. 
(1) Thin (less than one-eighth 
of an inch in diameter). 
(2) Thick (more than one-eighth 
of an inch in diameter, 
often three-sixteenths or 
more). 
F. Presence or absence of star. 
(1 ) Star present. 
(2) Star absent. 
"While most of these characteristics are very important, some of 
them vary so much under different environmental conditions that 
their use in a key is of doubtful value. The size of the leaf and size 
and length of the stem vary so much under different soil and climatic 
conditions that measurements made under one set of conditions do 
(4) Veins all green. 
H. Arrangement of hair on the upper 
surface of the leaf, if any. 
(1) Hair all over. 
(2) Chiefly on tips and along 
veins. 
(3) Absent. 
I. Outside color of the roots. 
(1) White. 
(2) Yellow, golden, or bronze. 
(3) Yellow, red, or pinkish. 
(4) Red or purple. 
J. Color of flesh of the roots. 
(1) White. 
(2) Cream colored or yellowish 
white. 
(3) Pinkish white or pinkish 
yellow. 
(4) Pinkish orange. 
(5) Marked with purple. 
K. Distinctness of wood elements in 
the root. 
(1) Distinct. 
(2) Blurred. 
(3) Not visible. 
