THE PINE. 



887 



tation becomes active, and the shoots proceed towards 

 their developement, a process which commences at the 

 lower part of the tree, and proceeds regularly upwards, 

 the leading shoot produced from the topmost bud, being 

 the last to be developed. 



The leaves, as already stated, are linear, acicular, and 

 persistent,* in some species remaining for many years upon 

 the tree ; they vary also in their disposition, in some 

 being single, and placed in horizontal rows along the 

 branches, or what is termed pectinate, as seen in the 

 silver fir (Picea pectinata) ; in others, as the spruce fir 

 (Abies excelsa), they stand in different directions around 

 the branch ; in others, again, they are placed in bundles, 

 enclosed in a common sheath, varying from two to six 

 in number, and these different arrangements of the leaves, 

 as might be expected, have been seized upon by botanists 

 to facilitate the sectional and generic divisions of the group. 

 In genus Pinus the leaves are in bundles, and much longer 

 than in those genera in which they are single, such as 

 Abies, Picea, &c. In Cedrus and Larix, however, though 

 many of the leaves spring in a tufted manner from the 

 lateral buds or diminutive branchlets, they are not, cor- 

 rectly speaking, in bundles like those of the true Pines, 

 as they have no common enveloping sheath, but are placed 

 singly, as a close examination of these buds, as well as 

 the leaves of a leading or extended shoot of either tree, 

 will clearly show. The longest-leaved species of genus 

 Pinus are such as grow in the warmest temperature ; 

 thus, the leaves of the Pinus Australis, Michaux, are 

 from a foot to a foot and a half in length, and again those 

 of the Pinus pinaster, and some of its near allies, are 



* In the southern Pines we have exceptions in genera Cunningltamia and 

 Dammant; in the first they are lanceolate, in the second oblong. 



2 c 2 



