oi'OiN'GiOLiis, (33 



than there is now demand for> Such buds are, therefore, merely adventitious. 

 On this account it would seem that those roots, commonly so calfed, which do 

 naturally and uniformly produce buds, are -n-ith propriety described by modern 

 writers as subterranean stems ;,&s the root-stalk of the sweet flag (Calamus), the 

 bulb of the tulip, or the ttiber m the j)otato. ) 



141. The summit of the root, or that part which connects it to 

 the ascending axis, is designated(as the collum, or neck. 



a. Strictly spealdng, this is the only stationary part of the plant. Occupying 

 the centre of motion between the ascending and descending axis, every enlai-ge- 

 raent that takes place upon its upper suiface arises into the air, wliile all below it 

 descends into the earth. 



142. The parts of the root wliich require especial notice, m-e 

 the taudex, fibrils, and spongioles. • 



a. The caudex (stock)^s the main body of the root. 



b. The FiBRiLsire the finer branches of the root, sent off 

 from the caudex.} These are the true roots. 



c. The spoNGioLES'/'are the tender and dehcate extremities of 

 the fibrils; and, since the latter lengthen only by accretions 

 made to these extremities, these are their growing points\ 



143. The form of the roo/is much diversified in different 

 plants,' but the principal varieties wliich have received distinct- 

 ive names, are the foUoAving : — 



144. Ramose (brandling). .Tliis root consists of ramifications 

 sent oif from the main root, hke tlie branches of a tree, but in 

 no determinate order. Such are the roots of most trees and 

 shrubs.-. (Fig. 20.) 



a. There is a strong analogy bet\veen the roots of a tree and its branches. In 

 many instances they may be made to perfoi-m, each, th^fTunctions of the other; 

 that is,fthe tree may be inverted, and the branches -s^-ill+econie roots and the roots 

 put forth leaves like the branches. The ■\\alloYv and the maple may be thus 

 mverted without injming their vitality.V 



b. A branch may often be made to put forth roots instead of leaves. If a 

 branch (offset) of th^willow or currant (Ribes) be inserted into the ground, cither 

 by the lower or the upper end, or by both at once, it will take root and flourish. 

 Other trees, as the mulberry (Moras) may be multiplied by layers. A branch is 

 bent and inserted into the ground by the apex. When it has taken root it is 

 severed from the parent stock, and becomes a perfect tree. 



c. The roots of a tree extend in all directions, and to considerable distances. 

 This distance is at least equal to the extent of the branches, and often much 

 greater. Those of the elm embrace an ai-ea of 300 feet diameter, of the poplar, 



