Picea. CONIFERS. 127 



Wisconsin and Minnesota, and along the Alleghany Mountains to the 

 high peaks of North Carolina. 



A tree 15 to 21 metres in height, with a trunk 0.60 to 0.90 metre in 

 diameter ; light, dry, rocky soil, forming, especially north of latitude 50°, 

 extensive forests on the water-sheds of the principal streams or in cold, 

 wet swamps ; then small, stunted, and of little value (P. rubra). 



Wood light, soft, not strong, close, straight-grained, compact, satiny ; 

 bands of small summer cells thin, resinous ; resin passages few, minute ; 

 medullary rays few, conspicuous ; color light red or often nearly white, 

 the sap-wood lighter ; largely manufactured into lumber, and used in 

 construction, for ship-building, piles, posts, railway-ties, etc. 



3S3. Picea alba, Link. 

 White Spruce. 



Newfoundland, northern shore of Labrador to Ungava Bay, Cape 

 Churchill, and northwestward to the mouth of the Mackenzie River and 

 the valley of the Yukon River, Alaska; south to northern Maine, north- 

 eastern Vermont, northern Michigan and Minnesota, the Black Mills of 

 Dakota, the Rocky Mountains of northern Montana, Sitka, and British 

 Columbia. 



A tree 15 to 50 metres in height, with a trunk 0.60 to 0.90 metre in 

 diameter ; low, rather wet soil, borders of ponds and swamps : most com- 

 mon north of the boundary of the United States, and reaching its greatest 

 development along the streams and lakes of the Flathead region of north- 

 ern Montana at an elevation of '2,500 to 3,500 feet ; the most important 

 timber tree of the American subarctic forests north of latitude 60° ; its dis- 

 tribution southward in British Columbia not yet satisfactorily determined. 



Wood light, soft, not strong, close, straight-grained, compact, satiny ; 

 bands of small summer cells thin, not conspicuous ; resin passages few, 

 minute; medullary rays numerous, prominent; color light yellow, the 

 sap-wood hardly distinguishable; largely manufactured into lumber, 

 although not distinguished in commerce from that of the black spruce 

 (P. nigra). 



384. Picea Engelmanni, Engelm. 

 While Spruce. 



Peace River Plateau, in latitude 55° 40', through the interior of 

 British Columbia and along the Cascade Mountains of Washington and 

 Oregon to the valley of the Mackenzie River ; on the principal ranges of 

 the Rocky and Wahsatch Mountains to the San Francisco Mountains, 

 Sierra Blanco, and Mount Graham, Arizona. 



A large tree, 24 to 46 metres in height, with a trunk 0.90 to 1.20 

 metres in diameter, or at its extreme elevation reduced to a low, prostrate 

 shrub; dry, gravelly slopes and ridges between 5,000 and 11,500 feet 

 elevation ; the most valuable timber tree of the central Rocky Mountain 



