STERILITIES OF WILD A^ T D CULTIVATED POTATOES. 31 
SUMMARY. 
The nonblooming habit of the potato with early abscission of the 
flower buds and flowers when grown under certain conditions is a 
direct influence of environment. Varieties which bloom in profusion 
in northern Maine rarely or never bloom at the New York Botanical 
Garden. This habit is a most decided limitation to fruit production, 
irrespective of the condition of pistils and stamens when flowers are 
produced. 
Relatively few of the cultivated varieties and seedlings produce 
viable pollen in considerable quantities and are able to function as 
pollen parents. The highest potency of pollen in these is decidedly 
low. 
Nearly all varieties, if not all, are able under conditions of favorable 
blooming to produce seed balls in response to proper pollination 
with viable pollen. 
As a group, the cultivated varieties of the potato exhibit a one- 
sided sterility which chiefly involves maleness. 
There is no conclusive evidence of a real physiological incompati- 
bility in the fertilization of cultivated varieties, but there is positive 
evidence of such sterility in the wild species, Solanum chacoense. 
F x hybrids between S. fendleri and S. chacoense appear to be 
completely impotent as males and also as functional females. 
Breeding from seed in potatoes can best be undertaken when 
varieties bloom in profusion. Under such conditions success in 
obtaining seeds depends chiefly on the use of pollen that is viable. 
So far as this- study has been made, pollen in anthers of fully 
mature flowers of any one variety appears to be very constant in 
quantity, range of abortion, general character, and viability. 
The production of tubers in which much food is stored does not 
directly influence and prohibit the formation of fruit by the potato. 
LITERATURE CITED. 
(1) Breeze, Mabel S. G. 
1921. Degeneration in anthers of potato. In Gard. Chron., ser. 3, v. 70, p. 
274-275. 
(2) Darwin, Charles. 
1868. The variation of animals and plants under domestication, v. 2, 568 
p. New York. 
(3) Dorset, M. J. 
1919. A note on the dropping of flowers in the potato. In Jour. Heredity, 
v. 10, p. 226-228, fig. 19. 
(4) East, Edward M. 
1908. Some essential points in potato breeding. In Conn. Agr. Exp. Sta., 
31st/32d Ann. Rpt. (Bien. Rpt.), 1907/1908, p. 429-447, fig. 8. 
(5) Garner, W. W., and Allard, H. A. 
1920. Effect of the relative length of day and night and other factors of the 
environment on growth and reproduction in plants. In Jour. Agr. 
Research, v. 18, p. 553-606, pi. 64-79. 
(6) Gesner, Conrad. 
1577. Epistolarum medicinalium . . . libri III. 140 p., illus. Tiguri. 
(7) Goebel, Karl. 
1900. Organography of plants. Pt. 1, xvi, 270 p., 130 fig. Oxford. 
