THE FARM STREAM 



35 



the swiftest current, or trailing down the 

 ledges in the waterfall, or encircling the 

 piling where the waves wash it constantly. 

 It is of a bright green color. There are apt 

 to be various other algas also, some forming 

 spots and blotches of blue-green color on the 

 surfaces of rocks, where partly exposed at low 

 water, and others forming little brownish 

 gelatinous lumps like peas lying on the 

 stream bed. Of the higher plants there will 

 be hardly any present in the rapids : per- 

 haps, a few trailing mosses or other creepers 

 rooted in the crevices at the edge of the cur- 

 rent, and just escaping annihilation at every 

 flood. 



In quiet waters covering muddy shoals wllVowln whorb 

 the vegetation is richer and more varied. 

 The dominant plants are seed plants. 

 Some of these (such as are shown in Figs. 12 

 and 13) grow wholly submerged. A few grow 

 rooted to the bottom, but have broad 

 leaves (Fig. 14) that rest upon the surface. 

 A few small plants (Fig. 15) float free upon the surface in the 

 more sheltered openings. And there are many rooted in the 



Fig. 13. Leaf-form 

 in three common sub- 



surrounding the stem 

 at the nodes: a, the 

 common water-weed 

 (Elodea canadensis or 

 Philotria canadensis) ; 

 b, the water horn- 

 wort (Ceratophyllum 

 demersum); c, the 

 water milfoil (Myrio- 

 phyllum). 



Fig. 14. Outlines of four common kinds of floating leaves: a, the floating river- 

 weed (Potamogeton naians) ; b, the spatter-dock (Nymphaa advena) ; c, the white water- 

 lily (Castaillia odorata); d, the water shield {Brasenia peltata). 



