114 GENERAL BOTANY 



just long enough to bring the leaves above the surface. 

 This is because the leaf-stalks of this plant are capable 

 of continual growth, and keep on lengthening when 

 darkened, i.e. in correspondence with the depth of the 

 sand that accumulates over them. 



Another plant very commonly found on sandy places 

 is LAUNEA PINNATIFIDA. It can be recognized at 

 once on the seashore by the rosettes (fig. 25) of 

 grayish green leaves dotted about on the sand. If 

 one be pulled up, there will be found below the 

 leaves a thick axis which runs vertically down into 

 the sand and ends in roots. On it are the scars of 

 old leaves, showing that it is of the nature of a 

 shoot (stem) not a root. 



6. A shoot axis (stem) which, like this, is under 

 ground, is termed a root-Stock. In LAUNEA nearly 

 every plant is attached to some other one by a thin 

 leafless branch which runs along the surface. This 

 is a branch with very long internodes and but few 

 leaves, from the nodes of which roots are developed. 

 An axillary bud then grows out and becomes a short 

 vertical axis with many leaves crowded into a rosette, 

 i.e. with very short internodes. This axis thickens, 

 and as the sand drifts over it, grows slowly upwards, and 

 so becomes a new plant, connected by the long inter- 

 node of the horizontal branch to the original plant. 



A horizontal branch of this kind, which starts a 

 new plant some distance off from the parent, is termed 

 a stolon. Other plants have branches which run 

 horizontally, but always under ground. New plants 

 rise as axillary buds on them, or by the end turning 

 upwards. Such branches are also termed runners. 



