Technical Bulletin No. 82 



TYPES OF FLOWERS AND INTERSEXES IN 



GRAPES WITH REFERENCE TO FRUIT 



DEVELOPMENT* 



A. B. STOUT f 



INTRODUCTION 



The types of flowers in grapes have long aroused interest among 

 both the growers and the breeders of grapes who are concerned not 

 only with the quality and the productiveness of seeded varieties, 

 but with the development of the seedless or partially seedless varieties. 

 Breeders of grapes are also finding it desirable, if not necessary, to 

 determine as fully as possible how the development of the desirable 

 distribution of the sexes in the flowers may be regulated, controlled, 

 or influenced by breeding and by selection of parentage. 



It is well recognized that the production of fruit in any variety 

 and in any seedling plant depends, first of all, on the development of 

 stamens and pistils and their power to function as sex organs in 

 fertilization and in fruit and seed formation. This is well illustrated 

 by the flower types of the best varieties of grapes now in general 

 cultivation. 



Self-fruitful varieties like the Delaware, Niagara, Winchell, and 

 Concord have flowers in which both stamens and pistil are well 

 developed and highly functional inter se. The stamens are en ct 

 or upright (Figs. 13-21) and their anthers contain pollen much of 

 which is viable and capable of functioning in fertilization. Both 

 kinds of sex organs are present and functional inter se in the same 

 flower. The plants are perfect hermaphrodites. They set fruit to 

 self-pollination. 



Other varieties like Brighton, Lindley, Barry, and Massasoit 

 have flowers whose stamens are recurved and more or less aborted 

 and the pollen which they contain is much shrivelled and defective, 

 and is entirely or almost entirely incapable of functioning in fertili- 



* This is the first report of work done in cooperation with the New York Botanical 

 Garden. 



t Director of the Laboratories, New York Botanical Garden. 



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