THE ROOT. 



69 



so called when some of the fibres are thick and fleshy, as in the 

 Asphodel, Crowfoot, Pseony, Orchis, and Dahlia. When the 

 fibre is enlarged in certain parts only, it is nodulous arid when 

 the enlargements occur at regular intervals, it is moniliform 

 (necklace-like). When it bears little tubers here and there, as 

 in Squirrel-corn (Dicentra Canadensis), it is tubercular. 



244 



Z41, Preony fibro-tuberon? roots. 242, Ginseng fusiform root. 243, Pelargonium triste moniliforro 

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



'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. 



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, Trum- 

 pet-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 origi- 

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

 frequently puts forth such roots from its lower joints, and thereby becomes strongly 

 braced. The Screw Pine (Pandanus) of the conservatories puts forth fulcra often several 

 feet in length. 



207. The Banian Tree (Ficus Indicus) drops "adventitious" roots from its ex- 

 tended branches, which, reaching and entering the ground, grow to supporting columns, 

 like secondary trunks. Thus a single tree becomes at length a grove capable of shelter- 

 ing an army. 



208. Epiphytes (eti, upon, 9u<rov, a plant), a class of plants, 

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



