THE STEM. 93 



137. Among Cryptogamous plants, numerous Fungi are para- 

 sitic upon living, especially upon languishing vegetables ; others 

 infest living animals ; the rest feed on dead or decaying vegeta- 

 ble or animal matters : all are destitute of chlorophyll (87), or any 

 thing like green foliage. It is not improbable that our Monotropa, 

 or Indian Pipe, a pallid and fungus-like Pha3nogamous plant, draws 

 its nourishment, at least in great part, from the decaying leaves 

 among which it grows. 



CHAPTER IV. 



OR ASCENDING AXIS. 



SECT. I. ITS GENERAL CHARACTERISTICS AND MODE OF GROWTH. 



138. BESIDES the direction of its growth, the descending axis or 

 root we have found to be characterized by producing nothing ex- 

 cept naked branches or subdivisions, and these in no definite order ; 

 by their continued extension through new formation at the extrem- 

 ity only, and in an uninterrupted manner, so as to give rise to no 

 joints or nodes, and consequently to bear no leaves (141) ; by the 

 absence of stomates in its epidermis (which, however, is the case 

 in all parts developed under ground) ; and commonly by having 

 no pith in the centre, or only a minute pith at the base, where it 

 joins the stem. The latter organ differs in nearly all these par- 

 ticulars. 



139. The Stem is the ascending axis, or that portion of the trunk 

 which in the embryo grows in an opposite direction from the root, 

 seeking the light, and exposing itself as much as possible to the 

 air. All Phsenogamous plants (110) possess stems. In those 

 which are said to be acaulescent^ or stemless, it is either very short, 

 or concealed beneath the ground. Although the stem always takes 

 an ascending direction at the commencement of its growth, it does 

 not uniformly retain it ; but sometimes trails along the surface of 

 the ground, or burrows beneath it, sending up branches, flower- 

 stalks, or leaves into the air. 'The common idea, therefore, that 

 all the subterranean portion of a plant belongs to the root, is by no 

 means correct. 



