12 
Colorado Experiment Station 
ference of main stems below the ground and above. Below ground 
the stems are smooth, while 
PLATE VII. 
Pearl Aerial and Main Stem Tubers. 
The result of removing natural tubers. 
above ground potato stems are 
squared by successive leaves 
whose bases spring from the 
stem. In Pearl bastard seedlings, 
which are strongly sexual, the 
stems are squared—even winged 
by the leaf stems. 
Color and Degeneracy .— 
With the old Peachblow, and 
with Pat's Choice and other va¬ 
rieties, the pink color follows the 
yoke lines, and strong color 
seems associated with sexual or 
degenerate tubers. With Ohios 
and improved Peachblows, th< 
better the conditions the lighter 
the color of the ruber, and the 
worse the conditions and the 
type, the deeper the red color 
the heavier the yokes and the 
deeper the eye pits or the more 
protruding the eyes. With 
Ohios, knots and seed ends are 
often of color diverse from that of 
the main tuber, or of other knots, 
possibly from varying influences 
during growth. Similarly, we 
often note different types on the 
same tuber, and we have a photo¬ 
graph of a Cobbler tuber, which 
is long, and in three sections— 
the first round, the second elong¬ 
ated, and the third a true Cobbler 
again. Peachblow tubers often 
project the main stem forward 
with all the end eyes and form 
either a new tuber or an end knot, usually of a darker red color. 
HYBRIDIZING. 
Ihe Pearl is one of our healthiest varieties, is medium early and 
a heavy cropper. If in a large selection of hybrids with the Rural we 
could find one plant which retained the desirable qualities of the Pearl 
with somewhat more of the balance and smoothness of the Rural tuber, 
the value to the Colorado industry would be great. At Del Norte, in 
1910, Francis Chisholm made sixty-seven crosses both ways between'the 
two varieties. Twenty-five seed balls were secured but a hail storm 
