THE SEED PLANTS 



283 



soil and supports the heavy stem and branches. The stem is 

 generally straight, and the branches usually rise in whorls. 

 The lower branches are longest, so that the whole tree pre- 

 sents a cone-like outline (fig. 219). A heavy bark of a kind 

 not seen in any of the 

 lower plants covers 

 the roots, stem, and 

 branches. Leaves are 

 borne only on the 

 younger branches. The 

 small scale leaves are 

 inconspicuous, while 

 the needle leaves are 

 the ones usually ob- 

 served. 



268. Needle leaves. 

 The needle leaves are 

 borne in pairs (fig. 

 220), in threes, fives, 

 etc., the number vary- 

 ing with the different 

 species. The number 

 of leaves in a cluster 

 is one of the distin- 

 guishing characteris- 

 tics of the species of 

 pines ; for example, 

 the white pine (Pinns 

 Strobus) has five leaves 

 in a cluster, the scrub 



FIG. 210. A white pine (Pinus Strobus) 



The stem is almost straight, the branches stand 



approximately at right angles to the stem, and 



the top is irregularly conical 



pine (Pmw divaricata) and others have two leaves in a cluster, 

 the Georgia long-leaf pine (Pinus palustris) has three, and others 

 have a variable number (from two to five) in each cluster. 



If one of the clusters of needle leaves is pulled away from 

 the branch that bears it, and its basal scale leaves are removed, 

 there will be seen a very small white branch upon which the 



