Structure of Grape Flowers 



I 2 3 



GRAPE FLOWERS (ENLARGED ABOUT 6 DIAMETERS) 

 (See Plates XXXVII., XXXVIII. and XXXIX. for flowers natural size.) 



There are three kinds of flowers in grapes, as shown in the cut greatly enlarged. 

 Fig. l,the practically pistillate flower, with weak, recurved stamens, generally incapable of 

 self-impregnation. 



Fig. 2, a staminate, or male, flower, with abundance of virile pollen. Non-bearing. 

 Fig. 3 represents the perfect, hermaphrodite, self-impregnating flower. 



Discussion of Sex and Impregnation in Grapes 



The vines producing male or purely staminate flowers are non-bearing in the very necessity 

 of their character, having no pistil, the part in bearing vines that develops into the grape. 



But the pistil in the great majority of cases will not develop into a grape unless one or more 

 of the ovules (female germs) within it have been impregnated by a pollen grain. 



Seedless Varieties 



In rare cases such development takes place without the ovules being impregnated, as in 

 Seedless Sultania and Sultanina (Thompson's Seedless), both of the Vinifera species. There is 

 no known way to produce seedless varieties at will. Such are accidental, yet we believe there 

 is a cause for such, whether practically controllable by human agency or not. The cause is 

 undiscovered. 



Nature's Method of Impregnation 



Nature's preferred method, and the only one we can practically apply, is to place pollen 

 grains upon the stigma, when in a receptive condition, which is shortly after the flower has opened, 

 and the stigma has thrown out a minute quantity of protoplasm upon its surface, appearing 

 moist. In this liquid the pollen grain germinates within 30 to 60 minutes, when the temperature 

 is 70 to 90, and the light, and fair weather present. Naturally, gentle winds and small winged 

 insects, which visit the flowers, carry pollen from flower to flower. The slender, thread-like 

 root of the pollen grain grows down one of the microscopic tubes in the style and pistil until 

 it comes against the ovule cell-wall, which it penetrates and then intermingles its substance 

 protoplasm with the protoplasm of the ovule, by pairing or grouping the chromosomes in new 

 combination. The pistil holding such impregnated ovule or ovules at once begins to enlarge, 

 and in time becomes a mature grape, and the ovules mature seeds within. 



As the male flower has no pistil it is clear that its vine cannot bear, unless the vine changes 

 its action from producing purely staminate flowers, to bearing pistillate flowers, which in two or 

 three instances only, in all my observation, have I known to occur. 



Male Vines should not be Neglected 



The male vines are certainly of value to the species or they would not have been developed 

 in nature. They come, by the law of division of labor ; in reproducing the species, and thus not 



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