I30 



ROOTS AND UNDERGROUND STEMS 



269. — Roots of Gerardia parasitic under- 

 ground {after GRAY) . 



185. Saprophytes are plants like the Indian pipes (Mono- 

 tropa) and squaw root {Conopholis) that live upon dead and 

 decaying vegetable matter. They are only partially par- 

 asitic, and do not bear the 

 haustoria of true parasites. 

 A good many plants that 

 appear to live an honest 

 life above ground practice 

 a secret parasitism by 

 sending their roots into 



those of their neighbors beneath the soil and drawing 

 part of their nourishment from them. Among those that 

 show a propensity to this degenerate habit are the pretty 

 yellow gerardias, and their kindred, the 

 yellow rattle {RMnanthiis\ and the 

 Canada lousewort {Pedicularis). 



186. Aerial Roots are such as have 

 no connection at all with the soil or 

 with any host plant, except as they 

 may lodge upon the trunks and branches 

 of trees for a support. In our climate 

 aerial roots are generally subsidiary to 

 soil roots, like the long dangling cords 

 that hang from some species of old 

 grape vines ; or they subserve other pur- 

 poses altogether than absorbing nourish- 

 ment, as the climbing roots of the trumpet vine and poison 

 ivy. 



187. Adventitious Roots is a name applied to any kind 

 that occur on the stems of plants or in other unusual posi- 

 tions. Common examples are the roots that put out from 

 the lower n6des of corn and sugar cane and serve both to 

 supply additional moisture and to anchor the plant more 

 firmly to the soil. Most plants will develop adventitious 

 roots if covered with earth or even if merely kept in con- 

 tact with the ground. The gardener takes advantage of 

 this property when he propagates by cuttings or layers. 



270. — A small orchid 

 with aerial roots, grow- 

 ing on the bough of a 

 tree (after GRAY) . 



