118 THE STORY OF THE PLANTS. 



is carried off by the visiting insect to the female 

 flowers on the next plant it visits. Indeed, you 

 may gather by this time how great a variety 

 of devices natural selection has produced for 

 securing this great desideratum of fresh blood, 

 or cross-fertilisation, from a totally distinct plant 

 colony. 



A much commoner English wild-flower than 

 the arrowhead shows us another form of early 

 threefold blossom. I 

 mean the water-plan- 

 tain (Fig. 21), a pretty 

 feathery weed, which 

 grows by the side of 

 most ponds and lake- 

 lets. In the water- 

 plantain you have a 

 flower of both sexes 

 combined ; it consists 

 of three green sepals, 



FIG. 21. FLOWER OF WATER- f nrrri j nfy o rirofppHvP 



PLANTAIN. The male and to m g a P 10 

 female parts are in the same cal y x '> tnree delicate 

 blossom. pinky - white petals, 



forming the corolla ; 



six stamens that is to say, two rows of three 

 each ; and a number of small one- seeded carpels, 

 exactly as in the buttercup, which occupies, in 

 fact, the corresponding place among the fivefold 

 flowers. 



But it is not often in the threefold flowers that 

 we get the calyx green and the corolla coloured, 

 as in these simple and very early types. Most 

 often in this great group of plants the calyx and 

 corolla are both brightly coloured, and both alike 



