13 



DISCUSSION AND CONCLUSION 



A summary of the variations in the flowers of cultivated varieties 

 of grapes and of seedlings from them shows that there are many 

 grades in the relative development of pistils and stamens. 



Complete loss of femaleness is seen in only a few cases, but various 

 grades of rudimentary pistils are present that are incapable of yield- 

 ing fruits of any kind. This evidence suggests that it is a weak 

 grade of femaleness which is responsible for the development of 

 seedless fruits. In near-seedless sorts, femaleness is of still another 

 grade but below that of high seed production. 



A complete morphological loss of stamens has not been found. The 

 least male plants are perhaps among those with recurved stamens, 

 small sterile anthers, and only aborted pollen. Such plants are 

 able to function as females only. Plants with erect crinkled stamens 

 and some plants with normal upright filaments are likewise unable 

 to function as males because of impotent pollen. In the extremes 

 there is complete loss of one or the other sex, at least functionally. 

 Between these extremes there are various grades of relative develop- 

 ment and functioning ability of pistils and stamens. In the per- 

 fect hermaphrodites both of these organs are highly developed and 

 functional, and it is these types that include all of the most important 

 and productive of the seeded grapes. 



It appears that, in individual plants, the stamens are more uni- 

 form than the pistils; at least they appear to be rather uniform 

 in respect to length of filaments and general character of anthers. 

 The intermixing of flowers of several types in the same cluster seems 

 to involve especially variations in the condition of the pistils. The 

 most obvious of these are mixtures of staminate flowers and of 

 perfect flowers that are capable of development into fruits with 

 seeds. The type of pistil that produces seedless fruits may also be 

 present. 



Variations in the character of pistils in flowers from year to year 

 have been observed. (See especially Detjen, 1917 for plant named 

 " Hope.") There is some evidence that the fruit production of the 

 self-fruitless varieties can be influenced by girdling and bending 

 (Beach, 1902), but whether such treatment changes the character 

 of the stamens by rendering them more potent as the results would 

 perhaps suggest is not determined. 



