yo FLOWERS OF LAKES, RIVERS, ETC. 



When floating, the flowers do not rise at the utmost more than 

 2 in. from the surface. It is in flower from April to August, and 

 is perennial. 



In the aggregate R. aquatilis the yellow base of each petal acts as 

 a honey-guide, and on it stands an oblique tubercle or wart-like projec- 

 tion, with a honey-secreting depression, which serves as a gland and re- 

 ceptacle for nectar. There are few anthers (8-20 stamens), which open 



Plioto. G. B. Dixon 



WATER BUTTERCUP (Ranunculus fluitans, Lam.), an Allied Species to show the Habit 



in succession when the flower opens, being turned to the centre. 1 The 

 anther-stalks later, twisting over the honey-glands, become immersed in 

 pollen, the stigmas developing, and coming in contact with the pollen 

 on the anthers. Visitors alight on the middle of the flower or on its 

 edge, and cause self-pollination or cross-pollination. When the surface 

 of the water rises the flowers remain submerged, and are self-pollinated. 

 The visitors are Diptera, Syrphidae, Eristalis, Helophilus, Chrysogaster, 

 Muscidae, Scatophaga, Hymenoptera, Apidse, Apis, Bombus, Coleoptcra, 

 Chrysomelidae, Helodes. The flower is scented. 



1 Next day the outer stamens move outwards and another whorl takes their place, and so on till all have 

 opened. 



