ROOT. 



11 



Roots are nodose 52 ; placentiform 53 ; conical 54 ; moniliform 55 ; testiculate, or 

 tubercular 56 ; coralline 58 ; tuberous 59 ; and fasciculate, when in clusters as in 

 the Asphodel. 



79. Occasionally the epidermis separates from the end of 

 the roots in the form of a cup or cap 57 , as in Pandanus and 

 Lycopodium. 



80. The power of affording nutriment to the stem and other 

 parts, is not possessed by the root exclusively in consequence 

 of its absorption from the soil. The root is often a reservoir 

 of nutritious matter ready formed, and consisting of starch, 

 as in the Dahlia ; mucilage, as in the Orchis ; alkaline matter, 

 as in Rhubarb ; upon which the young stem feeds, even al- 

 though the root itself is cut off from communication with any 

 source of supply. Moniliform, tuberous, testiculate, placenti- 

 form, conical roots, in short, all which are unusually thick- 

 ened, are intended by nature as reservoirs of food. They 

 must not be confounded with tubers (152), rootstocks (152), 

 or corms (153), all which are forms of stem. 



IV. STEM. 



81. The stem is produced by the successive developement 

 of leaf-buds (164), which lengthen in opposite directions. 



82. If an annular incision be made below a branch of an 

 Exogenous plant (95), the upper lip of the wound heals 

 rapidly, the lower lip not : the part above the incision in- 

 creases sensibly in diameter, the part below does not. 



