98 WEIGHT : THE GENUS DIOSPYROS 



been derived from a hermaphrodite type by sterilization 

 without reduction in number of parts. 



If the unisexual type was the primitive, the flowers are 

 now perhaps progressing towards the production of an 

 uniform hermaphrodite type. When one considers how 

 definitely monoecious or dioecious many other species are, 

 and that sterilization of sporogenous tissue is frequently met 

 with in the ontogeny and phylogeny of the higher plants, it 

 seems more reasonable to regard the more specialized 

 condition of unisexuality as the latest phase in development, 

 and, in view of other facts, to believe that the hermaphrodite 

 condition is the more primitive in this genus. The female 

 inflorescences in many species appear to have undergone 

 much abortion ; this is probably true of the parts of the 

 flower also. It is not meant to imply that the species 

 showing this condition are necessarily members of the most 

 primitive section of Diospyros. The statement is made 

 purely in relation to the evolution of sex in Diospyros, a 

 development which may or may not be correlated- with that 

 of the vegetative organs. 



It would therefore seem an easy task to derive the present 

 mixed sexual condition in D. hirsuta from a primitive 

 hermaphrodite flower. In the production of female from 

 hermaphrodite flowers the anthers, though persisting, 

 become barren. It seems more reasonable to regard a 

 staminode as being a stage in the abortion of a stamen, rather 

 than one in the development of a stamen towards fertility. 



If, however, we consider another species showing the same 

 variation in sex, viz., D. Thwaitesii, the evolution from the 

 hermaphrodite flower is more complicated. In this species 

 the staminodes are, as in the female flowers of D. hirsuta, 

 five in number and arranged on the corolla so as to alternate 

 with their lobes. In the male flowers, however, the number 

 of stamens always exceeds that of the staminodes of the 

 female flower, there being usually ten, and in one case 

 twelve fertile stamens present. It is interesting to note 

 that whttu there are ten stamens present these are arranged 



