CONIFERS. SILVA OF NORTH AMERICA. 103 



CONSPECTUS OF THE NORTH AMERICAN SPECIES 



ExTAEiES. Leaves flat, grooved above, stomatiferous on the lower and sometimes on the upper sur- 

 face, rounded and often notched, or on fertile branches frequently acute at the apex. 

 Resin ducts of the leaves within the parenchyma remote from the epidermis. 

 Bracts longer or shorter than the cone-scales. 



Bracts of the cone-scales oblong, rounded and short-pointed at the broad denticulate apex, 

 much longer than their scales, reflexed ; leaves dark green and lustrous above, pale 



below, obtusely short-pointed and occasionally emarginate 1. A. FkAseri. 



Bracts of the cone-scales oblong, emarginate and short-pointed at the broad serrulate apex, 



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shorter or rarely slightly longer than their scales ; leaves dark green and lustrous above, 

 pale below, rounded or obtusely short-pointed and occasionally emarginate, and on fertile 



branches acute or acuminate 2. A. baisamea. 



Bracts much shorter than the cone-scales. 



Bracts of the cone-scales oblong-obovate, laciniate, rounded, emarginate, and long-pointed at 

 the apex ; leaves blue-green and glaucous, stomatiferous above the middle on the upper 



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surface, obtusely pointed and occasionally emarginate, and on fertile branches thickened 



and acute " . . 3. A. lasiocaepa. 



Resin ducts of the leaves close to the epidermis of the lower side. 



Bracts of the cone-scales short-oblong, obcordate, laciniate and short-pointed at the apex ; 

 leaves dark green and very lustrous above, silvery white below, conspicuously emargi- 



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nate, or on fertile branches sometimes bluntly pointed 4. A. GRANDIS. 



Bracts of the cone-scales oblong, emarginate or nearly truncate at the broad denticulate 



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short-pointed apex ; leaves pale blue or glaucous, stomatiferous on the upper surface, 

 rounded, acute, or acuminate; on fertile branches often falcate, and thickened and 



keeled above 5. A. concolor. 



Bracts of the cone-scales rhomboidal or oblong-obovate, gradually narrowed into long slen- 

 der tips, half as long as their scales ; leaves crowded, dark green and very lustrous above, 

 silvery white below, rounded, notched, or acute, or on fertile branches acute or acuminate, 



and occasionally stomatiferous on the upper surface 6. A. amabilis. 



BrACTEAT^. Leaves flat, slightly rounded, obscurely grooved, and without stomata on the upper 

 surface, similar on sterile and fertile branches ; tips of the bracts of the cone-scales elongated ; 

 winter-buds large, with thin loosely imbricated scales. 



Bracts of the cone-scales oblong-obovate, obcordate, produced into elongated rigid flat tips, 

 many times longer than their pointed glabrous scales ; leaves dark yellow-green above, 



silvery white below, acuminate 7. A. venustA. 



NOBILES. Leaves blue-green, often glaucous, stomatiferous on both surfaces, bluntly pointed, flat- 

 tened and grooved above or tetragonal on sterile branches, tetragonal, acute, incurved, and 



crowded on fertile branches. 



Bracts of the cone-scales spatulate, full and rounded and fimbriate above, long-pointed, in- 

 curved, much longer than and nearly covering their scales ; leaves distinctly grooved on 

 the upper surface, rounded and often notched on sterile and acute or acuminate on fertile 



branches ' 8. A. nobilis. 



Bracts of the cone-scales oblong-spatulate, acute or acuminate, or rounded above with slender 

 tips, shorter or longer than their scales ; leaves tetragonal, bluntly pointed on lower and 

 acute on upper branches 9* -A- MAGNIFICA. 



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