THE VEGETATIVE ORGANS OF PLANTS. 2538 
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. Morth 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 
Thornsby Park, a drain 16 feet deep was stopped en 
