100 WRIGHT : THE GENUS DIOSPYROS 



hermaphrodite and dioecious condition. It is important 

 to realize that here we have a species which is mainly dioe- 

 cious, but where the staminal whorls of male and female 

 flowers agree in number, if we regard a group in the male 

 as equivalent to one member in the female. 



In the species belonging to this group the production of a 

 pistillate flower is attained by sterilization of the male 

 sporogenous tissue (the anther still persisting) followed by 

 a reduction of pairs or groups to single members. The 

 original hermaphrodite flower still occurs on polygamous 

 trees and always possesses stamens of different sizes, the 

 innermost being the smallest. 



The accessory whorls of the male and female flowers of this 

 and in fact of all the other species are widely different, but since 

 the differences are those of size and form they may be neglected 

 in considering the evolution of unisexuality in Diospyros. 



If we now consider the species in Group B, D. acuta and D. 

 oppogiiJjLolia,, which are only known in the monoecious 

 condition, we find that they can be easily arranged in a 

 series to show the similarity in the whorls of male and 

 female flowers. In D. oppositifolia the female flowers 

 usually possess four epipetalous staminodes alternating with 

 the corolla segments. In one female flower there were eight 

 separate staminodes arranged so as to be alternate with and 

 opposite to the corolla segments, each being typical in 

 form and possessing a completely barren anther. In the 

 male flowers of this species there are always eight epipetal- 

 ous stamens usually paired, with the inner member the 

 shorter of the two, but each stamen is attached to the corolla 

 by its own filaments. The pairs invariably alternate with the 

 corolla segments, though this orientation is liable to variation. 

 The variation in the male staminal whorl is where the 

 members of one or more pairs are not exactly opposite one 

 another, a deviation from the normal which tends to simu- 

 late the occasional eight separate staminodes of the female 

 flower. It is therefore very easy to correlate the staminal 

 whorl of the male and female flowers of D. oppositifolia with 



