74 



The Firs 



pointed, more upright, incurved, and crowded than on sterile lower branches. In 

 cross-sections the leaves show two resin-ducts, close to the epidennis on the under 

 side in some species, in others well within the pulpy tissue of the leaf. 



The monoecious flowers, appearing in the spring, are produced in the axils of 

 the leaves of the last season's growth. The staminate flowers are short-stalked, 

 pendulous, oval, ovoid, or cylindric, subtended by an involucre of small scale- 

 like bracts which often persist for some time; the subglobose anthers open crosswise, 

 the coimective terminating in a short blimt apex. The pistillate flowers are lateral, 

 short-stalked, and erect, with two ovules at the base of the scales, which are 

 shorter than the papery bracts. The erect cones are cylindric to ovoid, frequently 

 covered by globules of a resinous exudation, ripening at the end of the first season, 

 their scales falling away from the persistent stout scarred axis. The densely over- 

 lapping scales are thin, curved inward at the usually rounded apex and gradually 

 narrowed to the base, those near each end of the cone sterile. The papery bracts 

 are longer or shorter than the scales and of characteristic outline. The two seeds 

 at the base of the scales are ovoid or oblong, usually acute at the base, somewhat 

 flattened and provided with an ample oblique, papery wing; the embryo, with 4 

 to 10 cotyledons, is surrounded by fleshy endosperm. 



The name applied to this genus is the ancient Latin name of the Fir, Abies 

 Picea (L.) Lindley, the old world Fir, which is the type of the genus. Ten species 

 are known to occur in North America: 



Eastern trees. 

 Bracts serrulate, mucronate, shorter than or but little exceeding the cone- 

 scales; leaves mostly obtuse; northern tree. 

 Bracts aristate, reflexed, much longer than the cone-scales; leaves mostly 

 emarginate; southern tree. 

 Western trees. 

 Bracts without elongated linear tips. 

 -Bracts shorter than the cone-scales or exceeding them but little. 

 Leaves flat; cones 0.5 to 1.5 dm. long. 

 Leaves blue-green, glaucous at least when young. 

 Resin-ducts within the pulp of the leaf. 

 Resin-ducts immediately imder the epidermis of the leaf. 

 Leaves silvery-white beneath, dark green above; resin-ducts im- 

 mediately under the epidennis. 

 Bracts obcordate, abruptly short-tipped; leaves notched. 

 Bracts rhomboid to obovate, gradually long-tipped. 

 Leaves mostly 4-sided; cones 1.5 to 2.8 dm. long. 

 Bracts much longer than the cone-scales, long-tipped, some of the 

 leaves 4-sided. 

 Tips of the bracts much smaller than the scales. 

 Tips of the bracts covering the cone-scales. 

 Bracts with elongated, narrowly linear flattened tips, two to three times as 

 long as the cone-scales; California tree. 



1. ^. balsamea. 



2. A. Fraseri. 



3. A. lasiocarpa. 



4. A. concolor. 



5. A. grandis. 



6. A. amdbUis. 



7. A. magnifica. 



8. A. shaslensis. 



9. A. nobilis. 



10. A. venusta. 



