104 



ORGANOGRAPHY. 



organs of the plant ; these pecaliarities will be referred to 

 hereafter, in the description of the organs of which they are 

 respectively modifications. 



Kinds of Stems. — We have- seen that the stem, when first 

 developed, always takes a diametrically opposite direction to 

 that of the root. In many instances this direction is continned 

 more or less throughout its life. In other plants, however, the 

 terminal bud either acquires an irregular direction, and the 

 stem runs along, or remains under, the surface of the ground ; 

 or it perishes altogether at a very early period, and an axillary 

 branch takes its place, which also, by developing laterally, will 

 likewise continue near the surface of the ground, or burrow 

 beneath it. From these peculiarities in the direction and growth 



Fig. 201. 



Fig. 202. 



Fig. 201. A portion of the stem of Fassi- 



fiora quadrangularis. v, v. Tendrils. 



Fig. 202. Part of the stem of the Vine. 

 V, V, V. Tendrils. 



of stems and branches, we have a number of modifications which 

 we proceed now to describe. These are best treated of under 

 two heads, namely, those which are aerial, and those which are 

 subterranean. We can, however, by no means draw a distinct 

 line between the modifications of stem which these two divisions 

 respectively contain, as certain forms occasionally pass from one 

 into the other, thus being both subterranean and aerial at diffe- 

 rent points, or at different periods of their course. 



1. Aerial Modifications of Sterna. — Of these the more impor- 

 tant are the runner, the offset, the stolon, the sucker, and the 

 rhizoine, 



a. The Eminer. {Fig. 203.) — This is an elongated slender 



