GYMNOSPERMS 



301 



The needle leaves (Fig. 248) are borne in pairs, in threes, 

 in fives, etc., the number varying with the different species. 

 The number of leaves in a cluster is one of the distinguishing 

 characteristics of species ; for example, the white pine (Pinus 

 Strobus) has five leaves in a cluster, the scrub pine (Pinus 

 divaricata) and others have two leaves in a cluster, the 



FIG. 247. An old pine tree (Pinus Strobus), from whose roots the sand has 

 been blown away, thus exposing the taproot and killing the tree 



The lateral roots have been removed from one side, but they show. at the right of 



the picture 



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

 may have a variable number (2-5) in each cluster. 



If one of the clusters is pulled from the branch and 

 stripped of its basal scale leaves, there will be seen a very 

 small whitish branch upon which the needle leaves grow. The 

 needle leaves are really continuations of these small branches. 

 The inward faces of the leaves are so arranged that all of one 

 cluster when put together compose a cylindrical leaf mass. 



