155 



The cultivated varieties of chestnuts are clonal varieties. Each 

 originated in a single seedling that was propagated vegetatively. 

 They differ rather widely in respect to the number of seeds that 

 are normally produced in a bur, the number ranging from one to as 

 many as seven or eight. They differ also in other phases of pro- 

 ductivity. Being merely branches of one original seedling, the 

 different plants of a variety are very uniform in such charac- 

 teristics as flower behavior and the requirements for fruit and 

 seed production. 



But all varieties are able to bear good fruit. No nurseryman, 

 horticulturist, or breeder ever propagates a seedling of any fruit 

 or nut crop and develops a clonal variety from it unless it has 

 borne fruit satisfactorily. But the first judgment of the fruiting 

 ability of a seedling and usually also of the first plants propa- 

 gated from it is nearly always based on performance in mixed 

 plantings where there is opportunity for cross-pollination. The 

 ability of the variety to bear fruit is thus demonstrated but there 

 is no clue to its requirements for pollination. If the variety re- 

 quires to be cross-pollinated before it will yield satisfactory crops, 

 this need first becomes evident when a tree is grown in isolation 

 or when trees of the variety are grown in solid blocks. 



Pollination seems to be a prerequisite for seed-setting by most 

 chestnuts. But this does not apply to all chestnuts, for Dr. Robert 

 T. Morris reports^ that plants of the American Chinquapin may 

 freely mature fruits with viable seeds without any pollination 

 whatever. This ability to produce seeds apogamously may also 

 appear in other chestnuts and especially in some of the hybrids 

 which have the chinquapin for a parent. 



But apparently most varieties of chestnuts require cross-polli- 

 nation before they will yield adequate crops of nuts containing 

 meats. It is not yet fully clear why this is the case. To deter- 

 mine this one must first give attention to the flowers as to their 

 ability to function, their behavior in development and the require- 

 ments for pollination and fertilization. 



The flowers of chestnuts are described as monoecious. It 

 should not, however, be taken for granted that the two kinds of 

 flowers are fully functional. A variety may produce fruit and 

 seeds and yet be more or less sterile as a male. The staminate 



1 Chestnut Blight Resistance. Journ. Heredity 5: 26-29, 1914. 



