IN CEYLON. 101 



one another and consequently to derive both from a common 

 sex type. 



In D. acuta the staminal whorl of the female flowers 

 consists of five epipetalous members alternating with the L A(^. 

 corolla segments. The male flowers have, according to 

 Hiern,* from four to five stamens, corresponding to the 

 number of accessory whorl segments, and presumably 

 alternating with those of the corolla. It would thus be 

 quite as easy to derive each sex from a common hermaphro- 

 dite flower as with D. oppositifolia. 



The male flowers of IX acuta, though usually possessing five 

 epipetalous stamens alternating with the corolla segments, 

 often have seven to nine epipetalous stamens, single or united h ^ 

 in pairs and of very unequal length. If the sexes in this 

 species have originated from a common hermaphrodite flower 

 then the original type may have possessed numerous stamens, 

 which in the evolution of the female flower have undergone 

 abortion at a quicker rate than in the male. The very small 

 stamens which occur when the total number is more than 

 five per male flower are perhaps in their last stages, and may 

 represent a phase passed through in the ontogeny of the 

 female staminal whorl from the hermaphrodite type. 



We have therefore seen that in considering flowers of 

 species which are (a) dioecious, monoecious, and polygamous, 

 and (b) monoecious only, the staminal whorls of the male and 

 female flowers are at the present time in general agreement 

 in number, form, and orientation, and the sexes in these 

 species can be derived from a hermaphrodite type of flower 

 having a relatively large number of stamens. In the remain- 

 ing groups, which are either dioecious only or dioecious and 

 polygamous, the relationships are more complicated. 



If we take the Group C, which shows the dioecious and 

 polygamous condition, we find a great variation in the 

 staminal whorl of the different species. The simplest 

 arrangement is perhaps in D. Gardneri. Each female flower 



* Hiern, Lc., p. 183. 



