THE VEGETATIVE ORGANS OF PLANTS. 253 



the coast, where the land is laid under water for weeks at 

 a time during its growth, and it succeeds equally well in 

 fields which are flowed from the time of planting to that 

 of harvesting. (Russell. North America, its Agriculture 

 and Climate, p. 176.) The willow and alder, trees which 

 grow on the margins of streams, send a part of their roots 

 into soil that is constantly saturated with water, or into 



Fig. 44. 



the water itself ; while others occupy the merely moist or 

 even dry earth. 



Plants that customarily confine their growth to the soil, 

 occasionally throw out roots as if in search of water, and 

 sometimes choke up drain-pipes or even wells, by the pro- 

 fusion of water-roots which they emit. 



At Welbeck, England, a drain was completely stopped 

 by roots of horseradish plants at a depth of 7 feet. At 

 Thorusby Park, a drain 16 feet deep was stopped en- 



