448 Minnesota Plant Life. 



kind of plant appears both as a lake-border and as a marsh 

 plant, as, for example, the common yellow pond-lily, which 

 may grow upon mud flats, or more ordinarily out a little dis- 

 tance in the pond. Of the shore and the bar plants a number of 

 different varieties belonging to various groups occur in Min- 

 nesota. Among the algae, the bass-weeds, so common as the 

 outer zone of shore plants in almost every Minnesota pond or 

 lake, are most prominent. In some ponds, especially the 

 smaller ones of swales, prairies or meadows, the water mosses 

 are abundant. These have a different adaptation from the 

 river mosses. They do not have strong holdfasts by which 

 to maintain themselves in rapidly flowing water, but are spongy 

 masses of vegetation and evidently near relatives of the carpet 



FIG. 221. Stream-side vegetation. Ironweeds, thoroughwort, mullein, sedge, speedwell and 

 shrubbery. Hydrophytic vegetation in water's edge. After photograph by Williams. 



mosses of the woods. When they fruit, the spore cases are 

 sometimes thrust above the surface of the water, but often 

 the spores are shed below the surface. To this group of 

 plants may be referred also the water lobelias, pipeworts, quill- 

 worts, the four-leafed water fern and others, including a variety 

 of flowering plants, such as the eel-grass, the water buttercups, 

 starworts, water-lilies, water smartweeds, floating arrowheads, 

 pondweeds and water milfoils. 



A number of different and interesting adaptational charac- 

 ters exist among the shore plants. Commonly, when alto- 

 gether submerged, they have very much divided leaves, as do 

 the water milfoils or water buttercups. If part of the plant 



