152 IP s t e I 6 i a 



or may be crowded together into fascicles borne 

 on special dwarf l:)ranches. 



The Ahictinece are widly distributed through 

 the boreal regions, the north temperate zone, 

 and the adjacent mountainous parts of the 

 tropics. From five to nine genera and about 

 130 species are recognized. Almost two-thirds 

 of the species, representing all but one of the 

 genera, inhabit the Pacific slopes of North 

 America and Asia. 



The following is a synopsis of the North 

 American genera of Abietinece. 



A. Shoots of two sorts, long and dwarf; leaves 

 of dwarf shoots fascicled. 



a. Only scale-leaves borne by the long shoots; 



foliage leaves persistent, in fascicles of 

 2-5 (rarely i or 6). Cones ripening the 

 second year; cone-scales more or less 

 thickened at apex. Piniis 



b. Foliage leaves deciduous, borne singly on 



the long shoots; those of the dwarf shoots 

 forming large fascicles. Cones ripening 

 in one season; cone-scales thin. Larix 



