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MISC. PUBLICATION 162, U. S. DEPT. OF AGRICULTURE 



little separate films in the bark. In either case it dies from time to 

 time, and is re-formed nearer the wood. 



Trees, like many other plants, bear flowers and reproduce by means 

 of seed. When the tree enters on its long winter rest, it has its next 

 year's buds already formed. With the coming of spring, these buds 

 expand and grow until they finally open into flowers or leaves. 

 Some trees, like the elm and red maple, blossom and set fruit before 

 the leaves open. The pussy willow and alder catkins burst forth 

 before the frost is fairly out of the ground. Other trees wait until 

 their leaves are partly grown before producing their blossoms, while 

 still others, such as the chestnut and basswood, do not flower until 

 early summer. 



Most of the cone-bearing trees, such as the pines, spruces, and firs, 

 also blossom in the early spring. The st animate (male) and pistil- 





Figure 3. — An abundant seeding of yellow-poplar. 



Nature has to make a bounteous provision for the survival of her tree families, 

 for only a small proportion of the seed scattered germinates. A still smaller 

 proportion of the seedlings live to reach maturity. 



late (female) flowers are usually found on the same tree, and their 

 color varies in the different species from yellow and orange to shades 

 of pink, rose, or purple. The pines, especially, produce large quan- 

 tities of pollen which is scattered by the wind. Geologically, the 

 conifers are very old, being contemporary with the plant growth 

 from which the coal deposits of today were formed. They still re- 

 tain the simplicity of floral structure which marked the vegetation 

 of those early times. 



Some trees mature their seeds rapidly and scatter them early in 

 the growing season. This gives the seedlings a long summer for 

 their first season's growth. Others, such as the nut trees, slowly 



