Minnesota Plant Life. 



189 



others, but may in groves reach the height of seventy or eighty 

 feet. The top is more pointed or spire-hke than that of the red 

 pine and the bark is rather thin and irregularly divided, a little 

 like elm bark. The leaves arise in pairs and are much shorter 

 than those of the red pine, varying from three-quarters of an 

 inch to one and a quarter inches in length. The staminate 

 cones are produced in clusters much like those of the red pine, 

 but smaller. The pistillate cones are nearly spherical in shape, 



Fig. 72. Rock-vegetation near Duluth. White pines, white cedars and junipers. After pho- 

 tograph by Williams. 



purple in color and appear on the topmost branches of the tree. 

 \Mien the pistillate cones mature during the second season of 

 their lives they are generally curved to one side, by which char- 

 acter they may be recognized and distinguished from the short 

 cones of the red pine. The seeds are small, winged, and black- 

 ish in color and the embryo plantlet has only four or five seed- 

 leaves. There is no difficulty in discriminating even between 

 the seedlings of the three species. The wood of the jack pine 



