VEGETA TIVE RETROD L'CTION. 



263 



leaves. They generally arise upon the stem, more 



from the leaves or the root. Upon 



the stem they usually take the place of 



shoots of other forms, developing from 



axillary buds (figs. 294, 296). If 



formed on leaf or root it is always from 



adventitious buds (fig. 293). 



Every possible gradation exists, from 

 the simplest to those with well-de- 

 veloped members, constituting a plant 

 of some size. They may be artificially 

 grouped as follows : 



364. {a) Buds. — In these the axis 

 is short and the leaves scale-like. When 

 most highly developed the quantity of 

 reserve food is considerable and the 



rarely 



Fig. 294. — Fleshy buds in axils 

 of the leaves of a lily (I. ili- 

 um bulbi/eruiti). Some- 

 what reduced. — After Van 

 Tieghem. 



.y^ 



v\/f 



t. 





3M : 



jL_I- 



1 



Fig. 295.— Pond weed iPolamogeton crispus). Detachment o) spe< i.il shoots, hibenuu - 



ula, which are to hibernate under water. The plant ./ has one oi these shoots at the 

 tip; B lias just loosened one, /;, which is sinking to the bottom. Two thirds natural 

 size.— After Kemer. 



