28 



THE BOOT, OR DESCENDING AXIS. 



1S5. The cirrhous roots 

 of certain climbing vines (Euro- 

 pean ivy, poison ivy, trumpet- 

 creeper) put fortli in great 

 numbers from tbe stem, serv- 

 ing for its mecbanical support 

 and no other known use. 

 Again, 



136. The fulcra of certain 

 endogenous plants originate 

 high up the stem, and descend- 

 ing obliquely, enter the soil. Of this kind 

 are the roots of the screvc-pine (Panda- 

 nus) of the conservatories, v?hich are often 

 several feet in length before reaching the 

 ground. The figure represents a screw- 

 pine which was wholly propped up by 

 roots of this kind as if on stilts. Sim- 

 ilar roots occur, in a smaller way, at the 

 lower joints of the Indian corn. 



137. The Banyan Tree (Fieus Indioa) develops 

 adveutitious 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 tq the earth. Hav- 

 ing penetrated the soU, these roots become supporting columns. The branches 



■--— rtAfiv' 



85. Screw-pine (Fandanue). 



I. Bnnyan (Ficiis Indloa). 



