70 !• LOWERS OF LAKES, RIVERS, ETC. 



W'luMi lloaiiii^, the- tlowers do not rise at the uimost more ilian 

 2 in. Ironi the siirtace. It is in tlowcr troni April to Auj^ust, and 

 is perennial. 



In the aggregate R. aqnatilis 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 







Photo. C. B. Dixnn 



Water Bitterci t (Ra)iii>iniliis fluilans. Lam.), ;ui Allied Species to show the Habit 



in succession when the flower opens, being turned to the centre.^ 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 tlower or on its 

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

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

 The visitors are Diptera. -Syrphida;, Eristalis, Hclophilus, Chryso_s;astei\ 

 Muscida;, Scatophaga, Hymenoptera, Apida;, Apis, Bonibiis, Coleoptcra, 

 Chrvsom(-lida-, Hclodcs. Ihe (lower is scented. 



' Next (lay the outer stamens move outwards and anollier whorl takes their place, and so on till all have 



opened. 



