HABIT AND FOLIAGE 



335 



These usually persist for several years, although the Larch, for 



instance, is deciduous. 



The needles are either borne on the ordinary long shoots 



(e.g. Yew, Fig. 201, a, and Silver Fir, Fig. 193, A), or, as in several 



common genera (Pinus, Larix, Cedrus, all members of the 



Abietineae), are restricted to special dwarf -shoots. These arise 



in the axils of scale-leaves on the long shoots, and bear a few 



dark-coloured scales below and a variable number of foliage 



leaves above. In the 



Pines the number of the 



latter is limited (five in 



Pinus strobus, two in P. 



sylvestris, Fig. 200, and 



only one in P. mono- 



phylla), and no further 



leaves are produced after 



the first season, the whole 



dwarf -shoot being shed at 

 the end of two or three 



years. On the other 



hand, in the Larch (Fig. 

 193, B) and Cedar 

 (Cedrus) , where the dwarf- 

 shoots are larger and bear 

 a tuft of needles, quite a 

 considerable number of 

 new leaves is formed 

 annually, although after 

 some years this production 

 ceases and the dwarf-shoots die away. These two Conifers also 

 differ from the Pines in the fact that the needles are not entirely 

 confined to the dwarf-shoots, since, during the first season's 

 growth, they occur on the long shoots also. It will be realised 

 that only the normal shoots contribute to the permanent branch- 

 system of the trees. 



In most cases the leaves are sessile, although those of the 

 Yew have a short stalk (Fig. 201, a). Their bases are often 

 fused with the stem for a short distance, and persist after the 

 leaves have fallen, leaving characteristic scars (e.g. Spruce Fir, 



FIG. 192. Branches of the Spruce Fir 

 (Picea excelsa) with three ripe cones. 

 [Photo : E. J. S.] 



