CHAP. II. 



ROOT. 



87 



iremity, when it is termed fusiform (or tap-rooted by the Eng- 

 hsh, and pivoiante by the French); or it dilates immediately 

 below the surface of the earth into a globose form, when it is 

 named turnip-shaped, as in the common turnip ; if it is ter- 

 minated by several distinct buds, as in some herbaceous plants, 

 it is called many-headed (multiceps). 



The roots of many plants are often fleshy, and composed 

 of lobes, which appear to serve as reservoirs of nutrunent to 



as in 



43 



the fibrils that accompany them_ 

 many terrestrial Orehideous plants, Dahlias, 

 &c. These must not be confounded either 

 with tubers or bulbs, as they have been by 

 some writers, but are rather to be con- 

 sidered a special form of the root, to which 

 the name of Tubercules {fig. 43.) would not 

 be inapplicable. In Orchis the tubercules 

 are often palmated or lobed ; in the Dahlia, 

 and many Asphodeleae, they hang in clusters, or are fasci- 

 culated. 



In internal structure the root diifers little from the stem, 

 except in being often extremely fleshy; its cellular system 

 being subject to an unusually high degree of developement in 

 a great many plants, as the Turnip, the Parsnep, and other 

 edible roots. In Endogens, the mutual arrangement of the 

 cellular and vascular systems of the root and stem is absolutely 

 the same ; but in Exogens, there is never any trace of pith in 

 the root. 



Sect. IV. Of the Appendages of the Axis. 



From the outside of the stem, but connected immediately 

 with its vascular system, arises a variety of thin flat expan- 

 sions, arranged with great symmetry, and usually falling off" 

 after having existed for a few months. These are called, col- 

 lectively, appendages of the axis; and, individually, scales, 

 leaves, bracts, flowers, sexes, and fruit. They must not be 

 confounded with mere expansions of the cuticle, such as ra- 

 menta, already described (p. 49.), from which they are kno^vn 

 by having a connection with the vascular system of the axis. 

 Till lately, botanists were accustomed to consider all these as 



G 4 



