OUR TREES IN WINTER. 39 



they must vary, and individually adapt themselves to the 

 changes of climate and surroundings, or perish. 



For numberless generations, plants have been slowly 

 adapting themselves to their appropriate places. Natural 

 selection and the survival of the fittest forms, for the 

 positions they are to occupy, have placed on the earth's 

 surface, the exact species in the exact positions best suited 

 for their development. In different climates and in dif- 

 ferent situations, the particular variety too, of the species 

 that can best sustain the local conditions to which it must 

 be subjected, is found. 



This is illustrated very clearly by some of our own 

 forest trees. One of the most widely distributed of 

 North American Coniferae, and one little changed in 

 appearance, is the Red Cedar. This tree is found as far 

 north as latitude 50°, and south to the Gulf of Mexico. 

 It extends also from the Atlantic to the Pacific in some 

 portions of our continent. At its northern limit it is 

 only a shrub ; on our own sterile hills, it becomes a 

 rugged tree and is of no little economic value for many 

 purposes ; while in the warmer climate of Florida, the 

 same species is confined to the swamps, and from it is 

 obtained the clear, soft wood, used the world over in the 

 manufacture of the best lead pencils. 



Many of the trees, familiar in our woods, become towards 

 the Arctic circle mere shrubs, as, for example, the Birches, 

 the June-berry, and the Spruce. Others of our native 

 flora, which here in New England are but shrubs, under 

 more favorable influences in a warmer climate, become 

 forest trees. Among such are the Chinquapin Oak and 

 the Magnolia. 



Amons; the trees having naturally a rather extended 

 distribution, and one of recent introduction into New 

 England, is the Douglas Spruce. This tree is a native of 



