238 PROPORTION" OF ROOT TO BRANCHES, [BOOK i. 



cortical integument : it is in direct communication with the 

 vascular system of the root, of which it is, in fact, only a 

 subdivision; and its apex consists of extremely lax cellular 

 tissue and mucus. This apex has the property of absorbing 

 fluid with great force, and has been called by De Candolle 

 the Spongiole or Spongelet. It must not be considered a 

 particular organ; it is only the newly formed and forming 

 tender tissue. In Pandanus the spongelets of the aerial roots 

 consist of numerous very thin exfoliations of the epiphloeum, 

 which form a sort of cup, apparently intended for holding 

 water for the supply of the roots. 



The proportion borne by the root to the branches is 

 extremely variable : in some plants it is nearly equal to 

 them, in others, as in Lucerne, the roots are many times 

 larger and longer than the stems; in all succulent plants and 

 in Cucurbits they are much smaller. When the root is 

 divided into a multitude of branches and fibres, it is called 

 fibrous: if the fibres have occasionally dilatations at short 

 intervals, they are called nodulose. When the main root 

 perishes at the extremity, it receives the name of pramorse, 

 or bitten off: frequently it consists of one fleshy elongated 

 centre tapering to the extremity, when it is termed fusiform 

 (or tap-rooted by the English, and pivotante by the French) : 

 if it is terminated by several distinct buds, as in some herba- 

 ceous plants, it is called many -headed (multiceps) . The turnip 

 has been occasionally referred to a root. But, from the 

 investigations of Turpin and others, there is no room to doubt 

 that the turnip, the radish, the cyclamen, and the elephant- 

 foot, are all distensions of the stem : either of the first 

 internode, or of the inferior prolongation of the stem 

 below the cotyledons and above the root. 



The roots of many plants are often fleshy, and composed of 

 lobes, which appear to serve as reservoirs of nutriment to the 

 fibrils that accompany them; as in many terrestrial Orchida- 

 ceous 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 considered a special form of the 

 root, to which the name of Tuber cules (fig. 46.) would not 

 be inapplicable. In Orchis the tubercules are often palmated 



