HIGHER PLANTS 



In nearly all ponds are plants which float free, entirely 

 unattached to the bottom; some of them are at the surface, 

 others just below it. They are the duckweeds, with little 

 dangling rootlets, the bladder worts, drifting unanchored, and, 

 in limy water, lush growths of horn wort. 



The plants included in this book are only the commonest 

 ones of ponds and brooks with two or three others, like the 

 pitcher-plant, which grow in water-sodden bogs or marshes 

 and are much visited by insects. The animal associations of 

 each plant are briefly mentioned; such partnerships as those 

 of the water-lily and the beetle, Donacia, (p. 279), and trage- 

 dies like those continually occurring within the leaf traps of 

 pitcher-plants and bladderworts. 



Aquatic Liverworts and Mosses — Bryophyta 



The liverworts and mosses make up the group of Bryophyta, 

 green plants closely related~to the algse and in classifications 

 placed just above them. They are small, green, shade and 

 moisture loving plants, which grow crowded in mats and clus- 

 ters. Most of them live in moist places on land; there are a 

 few in ponds but more often they grow in running streams; 

 only a small number can thrive in dry places. They absorb 

 water rapidly but having no storage cells they quickly lose 

 it again. Water goes out of their cells as easily as it does 

 from the skins of frogs and they cannot endure dryness much 

 better. 



Liverworts — HepaticcB 



Liverworts have some traits like the alg^ but though their 

 ancestors may have been aquatic, they are now in general a 

 land group and their forms and habits suggest the mosses. 

 The liverwort has a green leaf-like thallus, which carries on 

 the main work that in flowering plants is done by leaves and 

 roots. If a thallus is thin, chlorophyll develops in all its cells 

 and both sides are green; if it is thick, only the upper surface 



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