II CONIFER.E 383 



huge wooden radish, and bears only one pair of long- 

 ribbon leaves a yard or more in length. 



The cotyledons are long and narrow, varying in 

 number from two to nearly twenty ; when numerous they 

 seem to form a tuft. The Conifers are a ^^ery ancient 

 group, dating back to the later Palaeozoic periods. 



PiNUS 



This genus includes those Abietineae in which both 

 shoots and leaves are dimorphic; ; or, as regards the leaves, 

 polymorphic.'^ There are about seventy species, spread 

 mainly over the north temperate 'region, and nearly 

 equally divided between the New and the Old World. 

 The extension shoots grow rapidly, and during the 

 season more or less continuously, and are elongated. 

 The lateral shoots are either elongate or short and thick, 

 forming " spurs." These are axillary shoots, which 

 grow slowly and are soon arrested in their growth, so 

 that they do not materially lengthen between the 

 nodes, and probably serve as store-places for reserve 

 food or for water. They are surrounded by bud scales. 

 There are three principal forms of leaves : the cotyledons ; 

 the primordial leaves, which are often mere scales ; and 

 the adult leaves, which are sometimes single (P. motio- 

 phylla), but generally arranged in tufts of two, three, 

 or five (rarely more), on the ends of the spurs. The 

 number in a tuft is, as a rule, constant in each species. 



P. sylvestris (Scotch Pine). — The leaves are borne 

 in pairs on the dwarf shoots. The seeds have a wing, 

 formed by the separation of a layer from the upper 

 face of the mature cone scale. The pollen grains, 

 which are carried by the wind, are lightened by having 

 a hemispherical bladder at each end. The upper 

 side of each stamen is saucer -shaped, and, as the 

 stamens are one over the other, when the anther opens 

 the pollen falls into the saucer of the stamen below, 

 where it remains till it is jerked out by the next gust 

 of wind. The quantity of pollen produced by Pine 



' Masters, "A General View of the Genus Finns," Jo%i,rn. Linn. Soc. (Bot.) 

 XXXV. (1904). 



