1882.] 
23 
[Trelease. 
f 
long enough to bring its anther just out of the mouth of the 
flower. The stamen next to it then lengthens, bows over the 
stigma, and in its turn sheds its pollen, later becoming erect. The 
stamens succeed each other in this regular order until all are 
mature, when the style elongates bringing the receptive stigma 
first in the position previously occupied by the dehiscing anthers, 
and finally to or just beyond the mouth of the corolla, fig. 19. 
This process goes on very slowly in the greenhouse, several 
days elapsing between the dehiscence of the first anther and the 
maturation of the stigma. If unfertilized, the stigma retains its 
freshness for an undetermined length of time, certainly a consid- 
erable number of days. In this form of protandry the slow 
development of the stamens in succession greatly prolongs the 
stage in which the flower is functionally staminate ; while the 
pistillate stage may enjoy an equal longevity if necessary. 
Small and middle-sized bees are the probable agents in fertil- 
izing Diosma. Such insects, in quest of nectar, are doubtless 
aided in their search by the yellow anthers in the throat of 
younger flowers, though too much stress should not be laid on 
the anthers as nectar marks, for obvious reasons. 
In a very young flower, whose stamens are all short and imma- 
ture, the only entrance is a small opening immediately over the 
stigma, and this does not give free access to the nectar reservoir. It 
will be remembered that at this time no nectar could be found ; 
hence the closure of the flower may prevent insects from wasting 
time in a search that can benefit neither them nor the plant. 
With the opening of the first stamen a new state of things begins. 
By its change in position the anther has now come to practically 
close the opening in the middle of the flower, but at the same time 
its removal from the side has opened two passages to the nectar , 
one at either side of its filament. After this the elongation of 
each stamen will open two more passages, till the maturation of 
the last has increased their number to ten, fig. 19. A bee in 
quest of nectar will naturally stand across the flower, facing the 
side it is working upon, while it probes the passages on either side 
of the filaments. In doing this its throat is necessarily brought 
in contact with the anther or stigma in the mouth of the flower. 
An examination of the floral structure does not show that 
self-fertilization is necessarily excluded. If the plant blooms un- 
