AXIS AND APPENDAGES. 69 



enlargement is of considerable interest, for it occurs at precisely 

 the point of greatest strain when the leaf is bent by the wind 

 or otherwise, and must serve to strengthen the stipe. 



The plant as a whole may be regarded as consisting of an 

 axis (the rhizome and its branches) which bears a number of ap- , 

 pendages in the form of roots and leaves. The axis forms the 

 central body or trunk of the plant, and in it most of its matter and 

 energy are stored ; the appendages are organs for taking in food, 

 for excretion, for respiration, for reproduction, etc. 



SPECIAL MOEPHOLOGT. 



Underground Part. The rhizome is a hard black, elongated, 

 and branching stem, generally flattened somewhat from above 

 downwards, and expanded slightly on either side to form well- 

 marked lateral folds the lateral ridges. Its width is seldom 

 more than half an inch, and is usually considerably less. In 

 transverse section it has the outline shown in Fig. 35, and the 

 marginal part only is black. The branches repeat in all respects 

 the form and structure of the main axis. Both end either in 

 conical, pointed and fleshy structures about two inches long, or in 

 blunt, yellowish knobs, plainly depressed in the centre. At these 

 ends the rhizome grows ; hence they are called the growing points 

 or apical ~buds (Figs. 31-3-1). 



Besides the apical buds the rhizome bears nearly always, here 

 and there, a number of dead, decaying tips, which are especially 

 numerous in old plants. They arise in the following manner: 

 After attaining a certain length both the rhizome and its branches 

 die away behind. Death of the hinder part follows at about the 

 same rate with which growth advances at the apical buds ; so that 

 the total length does not change materially from year to year. 

 It is obvious that this process must result in the gradual detach- 

 ment of the branches from the main axis. Each branch, now 

 become an independent rhizome, repeats the process ; and in this 

 manner a single original rhizome may give rise to large numbers 

 of distinct plants, all of which have been at some time in material 

 connection with one another. This process is evidently a kind of 

 reproduction, though it is not the most important and obvious 

 means for the propagation of the plant. In this way a large area 

 may be occupied by distinct, though related, plants whose branch- 



