ROOTS OF PLANTS 



47 



Fig. 13. Adventitious roots 



A leaf of brj'ophyllum removed from the stem will 

 put forth adventitious roots and shoots from the 

 notches on the edge, thus giving rise to new plants 



using for their other 

 contents. In addition to 

 the organic substances 

 and the useful mineral 

 salts that they contain, 

 these vegetables have a 

 relatively large bulk of 

 cellulose, which is help- 

 ful in stimulating the 

 activities of the intes- 

 tines (see p. 1 17). 



Fleshy roots are used 

 in large quantities as 

 fodder for cattle. To some extent roots are also used as 

 sources of drugs and flavoring materials. Among the latter 

 the most important are the 

 extracts of the licorice root, 

 the sassafras root, and the 

 sarsaparilla root. 



Because of the close ad- 

 hesion of the root hairs to 

 the grains of sand in the 

 soil, roots are very effective 

 agents in binding the soil, 

 enabling the latter to with- 

 stand the eroding effects of 

 water as well as of wind. 

 For this reason certain kinds 

 of grasses are sometimes 

 planted on sandy strips, to 

 prevent the complete re- 

 moval of the sand by the Fig. 14. Prop roots 

 winds. The hillocks formed xear the base of the trunk the screw pine 

 bv clumDS of such plants {Pandanus) sends out prop roots in a manner 

 . similarto that of the Indian corn. (From photo- 

 may COntmue to enlarge for graph loaned by New York Botanical Garden) 



