254 CONSERVATIVE ORGANS. [LECT. VI. 



(C. natans) has a much better claim than the 

 sarmentose to be ranked as a variety of the 

 procumbent stem, as it is a real stem, and 

 lies floating on the surface of the water, throwing 

 out radicles from the under side : the Floating 

 Club-rush, Scirpus fluitans, is an example. 

 The term natans for denoting this position of 

 the stems of aquatics is of importance in a 

 systematic point of view, and is used in con- 

 tradistinction to sunk (demersus) ; which im- 

 plies that the stem lies below the surface, as 

 in common Horn wort, Ceratophyllum demer- 

 sum. 



Besides the diversity which prevails in the 

 position or direction of the stems, we perceive, in 

 glancing the eye over the vegetable kingdom, that 

 they present much variety, also, with respect to 

 general form. Thus, some are simple or undi- 

 vided, while others are divided and subdivided 

 into very minute ramifications. 



1. The UNDIVIDED or SIMPLE stem (C. sim- 

 plex) consists of one piece only, without any 

 branches bearing leaves; although the flower- 

 stalk may be divided ; as exemplified in knotty- 

 rooted Figwort, Scrophularia nodosa. When, 

 however, there is no division even of the flower- 

 stalk, but the whole stem is one rod or column 

 from the base to the summit, and is terminated 

 by a single flower, or a simple spike, it is 



