140 Flowers and their Pedigrees. 



flowers is to be found in the existing alisma tribe, 

 including our own English arrowheads and flowering 

 rushes. As a rule, indeed, it may be said that fresh- 

 water plants and animals tend to preserve for us very 

 ancient types indeed ; and all the alismas are marsh 

 or pond flowers of an extremely simple character. 

 They have usually three greenish sepals outside each 

 blossom, inclosing one whorl of three white or pink 

 petals, two or three whorls of three stamens each, and 



Fig. 31.— Single flower of Alisma plantago. 



a number of separate ovaries, which are not united, as 

 in the more developed true lilies, into a single capsule, 

 but remain quite distinct, each with its own individual 

 stiGfma or sensitive surface. Even within this rela- 

 tively early and simple group, however, several grada- 

 tions of development may yet be traced. I incline to 

 believe that our English smaller alisma, a not un- 

 common plant in wet ditches and marshes throughout 



