50 DorsEY: VARIATION IN FLORAL STRUCTURES OF VITIS 
B. M. Duggar, of Cornell University, under whom this work was 
done as a topical problem, for helpful suggestions and criticisms, 
to Professor U. P. Hedrick, of the New York State Experiment 
Station, for courtesy in the use of material, and to Mr. Ernest 
Dorsey for assistance in obtaining some of the data. 
SUMMARY 
Vitis is dioecious, polygamodioecious, or perfect. The flower 
forms which occur are the staminate, and the perfect (1) with 
upright and (2) with reflexed stamens. Individual vines either 
within the variety or species are quite distinct with respect to 
these flower forms. In Vitis the flower forms resemble those of 
the closely related genera, Cissus L., Ampelopsis Michx., and 
Parthenocissus Planch. The direction of the evolutionary changes 
in the flower forms is not entirely clear. 
The typical staminate cluster is larger than either form of 
the pistil-bearing. The typical grape flower is 5-merous, although 
about 30 per cent show a variation from this plan. The petals, 
nectariferous glands, and stamens correspond closely in number. 
The dehiscence of the corolla seems to result largely from a drying- 
out process rather than from being pushed off by the straightening 
out of the filaments. 
The number of stamens per flower was found to vary from 
three to nine, the variation being independent of the flower form, 
variety, or species. The flowers from different: clusters of the 
same vine show in general the frequency of distribution that is 
characteristic of the vine. Clusters from different vines may have 
different arrays. When the stamens are increased or decreased, 
the petals and nectariferous glands, in general, correspond in 
number. An increase in the number of stamens is associated with 
an increase in the number of carpels. In short, the numerical 
relations of the members of the floral whorls are commonly 
maintained. 
In occasional vines the stigma is, throughout, only partially | 
developed. This condition may be regarded as an intermediate 
form between the pistil-bearing and the staminate forms, both in 
structure and function. The staminate flowers have rudimentary 
pistils, in which the stigmas and ovules are abortive. 
