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 (Pinus 
Strobus) has five leaves 
in acluster, the scrub 
Fic, 219. 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 (Pinus 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 
