30 THE VEGETABLE WORLD. 
-other by the length of surface (as shown in the vertical section) 
and the fleshy consistence of the subterranean leaves. 
We now have to consider the structure of stems in different 
ar 
———_ = : 
—_=__=_. 
‘ — SS 
= —— ay 
SSS 5 SSS 
a 
TAFT: 
a) r 
SAPU 4 
Male g . as 
Fig. esas stem of Iris germanica. 
kinds of vegetables. In order to arrive at a correct idea of their 
structure let us consider, first, the stem of forest trees; secondly, 
that of palm trees; thirdly, that of aborescent or tree ferns. 
