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 algae also, some forming 

 sppts and blotches of blue-green color on the 

 surfaces of rocks, where partly exposed at low 

 water; others forming little brownish gela- 

 tinous 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 Fig. ,13. Leaf-form 



in three common sub- 



In quiet waters covering muddy shoals i^l^lf^^^ln whSS! 

 the vegetation is richer and more varied. 

 The dominant plants are seed plants. 

 Some of these (such as are shown in Figs. 1 2 

 and 13) grow wholly submerged. A few grow 

 rooted to the bottom but have broad 

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

 A few small plants (Fig. 1 5) float freely upon the surface, in the 

 more sheltered openings. And there are many rooted in the 



leaves grow in whorls 

 surrounding the stem 

 at the nodes: a, the 

 common water-weed 

 (Elodea canadensis or 

 Pkilotria 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 {PotamogeUm natans) ; &, the spatterdock {.NympjKBa lutea) ; c, the white water 

 lily (CasHUea odorata) and d, the water shield (Brasenia peltata). 



