344 



Aquatic Societies 



cover, and that support a considerable variety of more 

 scattering species. One of the most widespread of 

 these secondary forms is the beautiful marsh fern, 

 whose black rootstocks over-run the tussocks of the 

 sedges, shooting up numberless fronds. Scattering 

 semi-aquatic representatives of familiar garden groups 

 are the marsh bellwort {Campanula aparinoides), the 

 marsh St. John's wort (Hypericum virginicimi) and the 

 marsh skull-cap [Scutellaria galericidata) : these are 

 dwarfish forms, however, that nestle about the bases of 

 the taller clumps. With them are straggling prickly 

 forms, such as the marsh bedstraw [Galium palustre), 

 the white grass (Leersia) and the tear-thumb {Polygo- 

 num sagittatum, fig. 202). Strong growing forms that 

 penetrate the marsh cover with stout almost vine-like 

 stems are the marsh five-finger {PotentiUa palustris) the 



Fig. 203. A marshy pool \Yith flowers of the white water crow-foot rising 

 from the surface. 



