28 



THE ROOT, OB DESCENDING AXIS. 



185. The cirehous roots 

 of certain climbing vines (Euro- 

 pean ivy, poison ivy, trumpet- 

 creeper) put fortli in great 

 numbers from the stem, serv- 

 ing for its mechanical support 

 and no other known use. 

 Again, 



136. The fulcra of certain 

 undogenous plants oiiginate 

 high up the stem, and descend- 

 ing obliquely, enter the soil. Of this kind 

 fiTo the roots of the screvc-pine (Panda- 

 nus) of the conservatories, which are often 

 several feet in length before reaching the 

 ground. The figure represents a screw- 

 pine which was wholly propped up by 

 i-oots of this kind as if on stilts. Sim- 

 ilar roots occur, in a smaller way, at the 

 lower joints of the Indian corn. 



131. TheBantan Tebe (Ficus ludica) develops 

 ;i.Jv6utitioua roots on a grand scale. "When the 

 branches have stretched out so far as to need ad- 

 ditional support, they send forth adventitious roots, descending to the earth. Hav- 

 ing penetr.ated the soil, theso roots become supporting columns. The branches 



35. Screw-pine (Pandanna). 



J6 Bnnyan (Flcualndioa). 



