IK 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 
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 D. acuta, though usually possessing five 
epipetalous stamens alternating with the corolla segments, 
often have seven to nine epipetalous stamens, single or united 
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) dicecious, monoecious, and polygamous, 
and (&) 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 dicecious 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. Gardner!. Each female flower 
, u., p-183. 
