10 



ELEMENTS OF BOTANY. 



plant would assume a regular, symmetrical shape. But practically the 

 vast majority of such plants are unsymmetrical, mainly because the ter- 

 minal bud — that is, the bud terminating the main stem — is so much more 

 vigorous than the others, that having the start in the beginning it keeps 

 it and leaves the branches with comparatively little nourishment. In many 

 plants the growth of the terminal bud is so vigorous that the axillary buds 

 never unfold and the stem remains always simple — that is, not branched. 



But suppose some accident destroys the terminal bud : then the ax- 

 illary buds, especially those nearest the seat of the injury, are quickened 

 into activity, and a plant whose stem is naturally simple becomes branched. 



Fig. 15. — Solomons-seal — a subterranean stem (rhizome). 



Leaf parallel-veined. 



Again, some plants in germination have not one or two seed-leaves 

 only, but a cluster of them ; in these the branches normally assume a ver- 

 ticillate character. This is the rule in the pine family (Coniferce). Others 

 still which start with their leaves in pairs, at a later stage produce them 

 alternately ; here the branches are also alternate. And some plants have 

 forking branches, the growing bud ceasing activity at a certain point and a 

 pair of forking branches starting from the axils of the last developed leaves. 



This brief view of the growth of the stem and branches demonstrates 

 sufficiently that every plant in its development obeys a fixed law of its 

 being. Yet from a few primary forms arises endless diversity ! 



Many of the forms of stems have received distinctive names, which are 

 made use of in botanical descriptions, as simple, not branched ; erect, 

 growing straight up; ascending, arising obliquely ; twining, climbing 



