2 BULLETIN 1195, U. S. DEPARTMENT OF AGRICULTURE. 
plants, however, has been drawn, and no adequate survey of the 
varieties by studies of the viability of their pollen has been made. 
It is this which the writers of this bulletin have attempted. The 
large number of varieties and seedlings grown at Presque Isle., Me., 
on the experimental plats of the Bureau of Plant Industry, located 
on the Aroostook Farm of the Maine Agricultural Experiment Sta- 
tion, afforded an abundance of material for the study. For three 
years (1920, 1921, and 1922) several varieties, a few unnamed 
stocks of seedling origin, and many seedlings directly from seed 
were grown at the New York Botanical Garden for comparison of 
their flowering and fruiting habits under different conditions. As a 
basis for determining the ability of varieties to produce fruit the rec- 
ords of the controlled pollinations made in the Bureau of Plant In- 
dustry during the period from 1914 to 1922, inclusive, have been 
utilized. (See Table 1.) 
It is to be noted that any type of sterility or combination of several 
types which happens to be characteristic of an individual plant grown 
from seed is continued in the asexual progeny of that plant, except 
for possible changes in bud variations. Thus, in a clon such as the 
Irish Cobbler variety of potato all the plants are branches of one 
original seedling. If this plant was a sex intergrade with a femaleness 
well developed and with a low grade of maleness, the particular degrees 
to which maleness and femaleness were relatively developed, either 
uniformly or in cyclic changes for the plant, are maintained in fields 
of the variety grown years after. The same will be true in respect 
to other types of sterility which may be present, except perhaps 
sterilities due to the invasion of specific organisms or that may 
accompany the various infectious diseases. 
GENERAL SURVEY OF THE TYPES OF STERILITY IN THE POTATO. 
STERILITY DUE TO NONFLOWERING. 
The nonblooming habit is more or less strongly developed in the 
cultivated varieties of the potato and is a most decided restriction to 
fruit and seed production. Some varieties have even been considered 
completely nonblooming, at least in some localities. 
In an excellent account of the nonblooming habit in the potato, 
East (4) 1 concludes that "all varieties do bloom under conditions of 
environment to which they are adapted." He points out that there 
are numerous gradations between the nonblooming condition and the 
condition of profuse blooming, such as abscission of all buds before 
the flowers open, the opening of a few flowers which immediately fall, 
and the persistence of flowers for several days. In the first two condi- 
tions named, flowers can not function as females in seed production, 
and the production of viable pollen in such flowers is scarcely to be 
expected. 
Variations in blooming for a single variety, both in different localities 
in the same season and in the same locality in different seasons, are noted 
everywhere that potatoes are grown. Of 30 standard varieties grown 
at the New York Botanical Garden in 1920 and 1921 none produced 
flowers that opened. The same varieties bloomed in profusion at 
Presque Isle, Me., in the experimental plats of the Bureau of Plant 
Industry. At both places good crops of tubers were obtained. 
» Serial numbers (italic) in parentheses refer to "Literature cited," at the end of this bulletin. 
