ROOTS 



3S 



primary roots, that is, a cluster proceeding from the lower 

 end of the hypocotyl at the outset. If such roots become 

 thickened, like those of the sweet potato and the dahlia 

 (Fig. 17), they are known && fascicled roots. 



Fig. 14. Dodder growing upon a Golden-Rod Stem. 



s, seedling dodder plants, growing in earth; ft, stem of host; r, haustoria 

 or parasitic roots of dodder ; i, scale-like leaves ; ^, magnified section 

 of a portion of willow stem, showing penetration of haustoria. 



