CHAPTER IX 



WEEDS OF PONDS, RIVERS, AND DITCHES 



MANY plants are specially adapted to live in water, 

 either (i) floating free and unattached to the soil, in 

 which case they derive their nourishment entirely from 

 substances dissolved in the water ; or (2) with their roots 

 in the mud or soil forming the bed of the river or pond ; 

 in the latter case the materials necessary for growth are 

 taken by the roots from the soil, and also in part from 

 the water by means of the leaves of the plants. 



When allowed to grow without interference water 

 plants become troublesome in rivers, ponds, lakes, and 

 ditches, and much expense must be incurred in keeping 

 them down. Some of them choke the small streams 

 and ditches in which they grow, and prevent the free 

 drainage of water from adjoining land. Flooding of 

 low-lying areas may arise through the blocking of water- 

 courses by this class of weeds, and pasture and arable 

 land may thus be made less valuable for grazing pur- 

 poses or the cultivation of cereals and other farm crops. 

 Canals and navigable rivers are frequently made almost 

 impassable for traffic by the growth of water plants. 

 Boating and bathing in lakes, ponds, and rivers may be 

 rendered difficult and dangerous by them, and their 

 presence in abundance may ruin the water for angling 

 purposes. Skating may also be spoilt by floating weeds. 



Many plants found by the sides of streams and ditches 



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