STERILITIES OF WILD AND CULTIVATED POTATOES. 31 



SUMMARY. 



The nonbloomiiig 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 



f)ollen pai'ents. The highest potency of pollen in these is decidedly 

 ow. 



Nearly all varieties, if not all, jire 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, Solannm chacoense. 



Fj 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 tlie 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, lig. 19. 



(4) East, Edward M. 



1908. Some essential points in potato breeding. In Conn. Agr. Exp. Sta., 

 3l8t/.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 lig. Oxford. 



