40 



THE STEM, OR ASCENDING AXIS. 



189. The corm is an under-ground, solid, fleshy stem, with con- 

 densed internodes, never extending, but remaining of a rounded form 

 covered with thin scales. It is distinguished from roots by its leaf-bud, 

 which is either borne at the summit, as in the crocus, or at the side, as 

 in the colohicum and putty-root (Aplectrum). 



190. How THE cORM GROWS. The corm usuuUy accomplishes its part in vegeta- 

 tion in one or two seasons, and then gradually yields up its substance and life for 

 the nourishment of the new progeny formed from the axils of its upper scales in 

 case of the Crocus and Gladiolus, or the single new corm from the axil of a lateral 

 scale, as in Colchicum. 



5T, Corms of putty-root (Aplectrnm) ; o, of last year, 6, of the present year. 58, Scale bulb of 

 Tvhito lily. 59, Scale bulb of Osalis violacea. 



191. The Bulb partalvcs largely of the nature of the bud. It con- 

 sists of a short, dilated axis, bearing an oval mass of thick, fleshy scales 

 closely packed above, a circle of adventitious roots around its base, and 

 ■a. flowering stem from the terminal, or a lateral bud. 



192. How MULTIPLIED. Bulbs are renewed or multiplied annually at the ap- 

 proach of winter by the development of bulbs from the axils of the scales, which 

 increase at the expense of the old, and ulti- 

 mately become d^3tached. Bulbs which flow- 

 er from the terminal bud are necessarily either 

 annual or biennial : those flowering from an 

 axillary bud may be perennial, as the termi- 

 nal bud may in this case continue to develop 

 new scales indefinitely. 



193. Bulbs are said to be iunicated 

 when they consist of concentric layers, 

 each entire and enclosing all within it, 

 as in the onion. But the more com- 

 mon variety is the scaly bulb — consist- 





1 S'- 



ing of fleshy, concave scales 

 lily. 



60. Bulb of Lilium superbum, with habit 

 of a rhizome ; a, full-grown bulb sending 

 up a terminal stem c, and two offsets bb, for 

 the bu lbs of ne.ict year. 



arranged spirally upon the a.\is, as in the 



