82 



STRUCTUEAL BOTANY. 



[69, 70. 



and 



(necklace-like). When it bears little tubers here 

 there, as in Squirrel-corn, it is tubercular. 



205. Deposits of starch, or farinaceous matter, in 

 all these cases, constitute the thickening substance of 

 the root, stored up for the future use of the plant. 



214 



241, Paeony fibro-tuberous roots. 242, Ginseng fusiform root. 243, Pelargonium triste moniliform 

 root. 244, Spirea filipendula nodulous root. 245, A creeping stem, with adventitious roots. 



206. Adventitious roots are such, as originate in some part of the 

 ascending axis stem or branches whether above or below the ground. 

 They are so called because their origin is indeterminate, both in place and 

 time. Several special forms should be noticed; as the cirrhous roots of certain 

 climbing vines (European Ivy, Poison Ivy, Trumpet-creeper) put forth in great 

 numbers from the stem, serving for its mechanical support and no other 

 known use. Again : the Fulcra of certain Monocotyledonous plants originate 

 high up the stem, and descending obliquely enter the ground. The Indian 

 Corn frequently puts forth such roots from its lower joints, and thereby be- 

 comes strongly braced. The Screw Pine (Pandanus) of the conservatories 

 puts forth fulcra often several feet in length. 



207. The Banian Tree (Mcus Indicus) drops " adventitious " roots from 

 its extended branches, which, reaching and entering the ground, grow to sup- 

 porting cohimns, like secondary trunks. Thus a single tree becomes at length 

 a grove capable of sheltering an army. 



208. Epiphytes (err/, upon, <t>vr6v, a plant), a class of 

 plants, called also air-plants, have roots which are 

 merely mechanical, serving to fix such plants firmly 

 upon other plants or trees, while they derive their 



