THE BOOK OF NATURE STUDY 



These plants have many features in common ; the most im- 

 portant is the structure of the leaf, the organ which more than 



any other responds to the environment. 

 Some of these plants adapt themselves to 

 their surroundings by the reduction of their 

 leaf surface ; others by developing a water- 

 storage tissue which makes the leaf succulent. 

 The reduction of the leaf surface is one of 

 the means by which a plant prevents the 

 loss of water. In the Salicornia the leaves 

 are scarcely distinguishable from the fleshy 

 stem, immediately under the epidermis of 

 which are two rows of cells filled with chloro- 

 phyll granules. The same object of restrict- 

 ing the loss of water is attained in the 

 Marram Grass by the inrolling of the leaf, 

 and in other plants by the thickening of the 

 outer skin, or by a covering of hairs, or 

 the formation of a waxy layer, forming 

 the bloom which is so often noticed on 

 seashore plants. 



The stems of these plants also show special modifications 

 of structure. They have much less woody tissue, for there is 

 less conduction of water ; on the other 

 hand, they have a greater development 

 of assimilating tissue. Most of them 

 have creeping rhizomes. 



The low growth of many of these 

 plants is another noticeable feature ; 

 even shrubs are prostrate. The Creep- 

 ing Willow is a case in point. It is a 

 low, straggling shrub ; the stems creep 

 underground, rooting at the nodes, and 

 only ascend above the soil to a foot or 

 more. It has the regular type of 

 Willow leaf, and these are silky on 

 both surfaces. 



This stunted growth of plants is 



FIG. 3. Creeping Willow 

 (Salix repens}. 



FIG. 4. Stork's Bill (Erodium 



