200 THE NATURE AND WORK OF PLANTS 



Note the occurrence of shrubs and small bushes. 

 Are they found under trees or in openings or mar- 

 gins? In an open or mixed forest there may be 

 a continuous layer of shrubs over the entire area, 

 while in close woods they can find suitable con- 

 ditions only in the openings. Plot the positions 

 of the shrubs and determine the species repre- 

 sented. 



Climbers will be found in greater or less abun- 

 dance. Some of these will be attached to the 

 trunks of the tallest trees, while others are sup- 

 ported by the shrubs and low bushes. 



The carpet, or layer of plants which cling to 

 the surface or rise only a short distance above it, 

 will vary greatly with the manner in which the 

 trees are associated. In close pure forests, like 

 the hemlock, the carpet will be sparse and almost 

 entirely lacking from the depths of the wooded 

 area. A few low-growing species may be found 

 in open places or clinging to exposed rocks or 

 hillocks. In this carpet will be found mosses, 

 ferns, liverworts, creeping and trailing vines and 

 shrubs, and herbaceous plants which form tufts or 

 rosettes of leaves which lie close to the surface, 

 like the sedges, some grasses, or the saxifrages. 



