86 FOREST commissioner's REPORT. 



Botanical and Sii.vical Characteristics, 

 general appearance. 



Mature paper birch may be readily recognized by its creaniy 

 white bark, which separates readily into thin, papery layers. 

 Small twigs, and the stems of young trees up to an inch or two 

 in diameter, have a brownish bark, usually tinged with orange, 

 while near the ground on old trees the bark often becomes dark, 

 blackish, and broken into thick, closely appressed scales. The 

 bark not infrequently resembles that of the white birch, but can 

 be distinguished from it not only by its greater whiteness and 

 scaliness, but also by the fact that white birch has at the base of 

 the limbs dark, triangular patches which paper birch does not 

 have. Intermediate forms ccasionally occur in which the bark 

 resembles that of both species. Such specimens are sometimes 

 looked upon by woodsmen as hybrids. They appear, however, 

 to be merely variations from the type, due to different condi- 

 tions of site and growth, and can be readily classified by their 

 leaves and other characteristics. 



Forest-grown paper birch has a long, clear bole with a narrow 

 crown occupying usually a little less than half the length of the 

 tree. The twigs are fine and delicate and the foliage very light 

 and open. The open-grown tree is usually shorter with a much 

 shorter bole and a much larger, better developed crown. 



LEAVES, ELOWERS, AND FRUIT. 



The leaves of paper birch are ovate, irregularly serrate, with 

 short, broad points which distinguish them at once from the 

 very long-pointed leaves of the white birch. The winter buds 

 are dark chestnut brown, ovate, acute, and about one-fourth 

 inch long. They help to distinguish the tree from white birch, 

 since they and the twigs on which they grow are slightly hair\-, 

 while in white birch they are smooth. 



The birches are all monoecious, having the staminate and pis- 

 tillate flowers on the same tree. The staminate flowers occur 

 in long catkins, or aments, which are visible during the winter 

 and elongate and bloom in early spring. The pistillate flowers 

 occur in much shorter aments and are not visible during the 

 winter. They form a cone-like fruit, or strobile, on the scales 

 of which arc l)()rne the seeds. These are very small and light. 



