CHAP. XI.] BETULACE^. 187 



for its upright and close habit of growth ; its 

 leaves also are very peculiar in their shape, being 

 broad at the base and then tapering suddenly 

 to a point. The seeds resemble those of the 

 Black Italian Poplar in the quantity of wool 

 which they produce, but luckily the female plants 

 are extremely rare. There are many other 

 species, the most remarkable of which are the 

 Carolina Poplar (P. angulata)^ known by its 

 square stem and very large leaves ; the Balsam 

 Poplar, or Tacamahac tree (P. halsamifera) , the 

 buds of which are covered with a resinous 

 fragrant substance, and the leaves are of a 

 pale yellowish green, appearing very early in 

 spring ; and the Ontario Poplar (P. candicans)^ 

 which resembles the balsam Poplar, except in 

 its leaves, which are very large and whitish on 

 the under surface, and in the great rapidity of 

 its growth, while that of the Balsam Poplar is 

 rather slow. 



BETULACEtE.— THE BIRCH TRIBE. 



The plants included in this tribe have single 

 leaves, which are generally what is called feather- 

 nerved ; that is, the veins are marked strongly 

 and deeply from the mid rib to the margin. 

 The flowers are in cylindrical catkins, the male 

 and female flowers being on the same plant. 



