PARASITISM 



335 



nourishment from other organisms, either living or dead, 

 and so comprehends an enormous number of parasites. 

 Of these, familiar examples will be the "smut" upon 



ABC 



FIG. 112. Dodder, a parasitic seed plant. A, Magnified section of stem 

 penetrated by roots of dodder; B, dodder upon a golden- rod stem; C, seedling 

 dodder plants growing in earth; h, stem of host; /, scale-like leaves; r, sucking 

 roots, or hanstoria; s, seedlings. (A and C after Strasburqer. From Bergen 

 and Davis' "Principles of Botany." Ginn & Co., publishers.) 



corn and rye, the potato "rot," the grape-vine "mil- 

 dew," the various "rusts," and some of the leaf curls. 



