MESOPHYTE SOCIETIES. 247 



Not only is protection during the cold period secured 

 by deciduous forests through the falling of leaves, but the 

 development of scaly buds is an adaptation to the same end 

 By means of these overlapping, often hairy, and even var- 

 mshed structures, delicate growing tips are protected dur- 

 ing the cold season. The development of cork, also, on the 

 older parts, is a measure of protection. 



Although the trees are the dominant plants of a forest 

 society, it must not be forgotten that numerous other form 

 are associated with them. At a lower level stand the shrubs 

 below these the tall herbs, then the low herbs and grasses' 

 and finally close to the soil mosses and lichens". 

 These different strata, as they are called, represent differ- 

 up oft d m i r nce to light ' the lower strata bei »g ™a e 



up oUhade plants as compared with the upper strata. In 



olant 6 f t , e haWt ^ b6COme S ° estoblished * ™*J 

 pUnts of the lower strata that they depend upon the pros 



outthem ° Vershad0W1 "S str ^> ^d could not live with- 



The vernal habit is also an interesting feature of decidu- 

 ous forests. It is a matter of common observation that the 



Sfns bl7 °t " T™^ fl ° WerS " ° CC "'- S b f °™ t. and wooded 

 glens before the trees come into full foliage. The working 



season of these vernal plants is before the dense foliage of 

 the forest shuts off the light. Accordingly, they are mostly 

 geophilous m habit (see §146), sending up their shoots or 

 leaves with great rapidity from underground tubers, root- 

 s tocks, etc. and completing their vegetative work in the 

 short period during which the light is available. After the 

 forest leaves arc fully developed the spring flowers disap- 

 pear waiting in their subterranean retreats for the next 

 short period of activity. Two prominent forms of the ver- 

 nal habit may be observed. The loaves may appear before 

 the flowers, as ,n Brythronium and Hydrophyllum ; or they 



m ay^pearaftertbeflowcrs,a S in//, vw //,,, ,,,;,,;,„,„/ ,,]. 



One of the wild leeks (Allium tricoccum) has developed a 



