224- THE STRUCTURE OF FLOWERS. 



anthers, but to higher differentiations and an increase in the 

 quantity of pollen. Secondly, that the orders, with gyno- 

 dicEcism have the maximum of stamens, is not universally 

 true, Pelargonmm having only seven out of ten. Again, the 

 Labiatce are especially characterized by " entomophilous 

 structures." Lastly, the order Caryophyllece is multiovulate. 

 In the first two interpretations, those of Miiller and 

 Darwin, Miiller suggests scanty nourishment as a cause for 

 the diminished size of the female flowers, which might apply 

 to any or every protandrous plant and so give rise to gjno- 

 dioecism ; for if it be a sufficient cause in one family, why has 

 it not brought it about in all ? This cause alone does not 

 touch the question, Why is gynodioecism peculiarly common 

 in the Alsinece of the Caryophyllece and in Lahiatoi ? Mr. 

 Darwin thinks that an increased fertility of the female may 

 be the cause; but he seems to forget that no flower of the 

 Labiatce can bear more than four seeds, so that, supposing a 

 female plant to have the same number of flowers as a her- 

 maphrodite, if it bears more seeds it must be due to the 

 decrease in fertility of the latter, and not to any increase in the 

 former. * It is, in fact, a very common occuiTence for a flower 

 of any member of the Labiatce to bear one, two, or three only, 

 as well as four nutlets in an individual fruit. Mr. Darwin 

 " doubts much whether natural selection has come into play," 

 and notices that " the abortion of the stamens ought in the 

 females to have added, through the laAV of compensation, to 

 the size of the corolla," as is the case in the ray florets of 

 the gynomonoecious Compositce. He, however, recognizes the 



* In his experiment with Satureia hortensis, Mr. Darwin collected 

 seeds from the finest of ten female plants, and they weighed 78 grains ; 

 while those from the single hermaphrodite, which was a rather larger 

 plant than the female, weighed only 332 gi'ains j that is, in the ratio of 

 100 to 43 (Forms of Flowers,_-p. 303). 



