PINACEAE 



Douglas-fir 



Pseudotsuga taxifolia (Poir.) Britt. (Pseudotsugo menziesii Franco) 



HABIT. A large evergreen tree attaining a height of over 

 300 feet on the west coast and 130 feet in the Rocky Mountains; 

 compact, pyramidal crown, with irregularly disposed branches. 



LEA\"ES. Linear, single, more or less flattened, blunt to point- 

 ed, spirally arranged, and petiolate; Y^-UA inches long; grooved 

 above and stomatiferous below; persistent 5-8 years or longer. 



FLOWERS. Monoecious; male orange-red; female red-green. 



FRUIT. Pendent, woody cones; 2-4Vi inches long, oblong- 

 ovoid, maturing in one season; scales thin, rigid, rounded, 

 much shorter than their long, exserted, 3-lobed bracts. Seed: 

 %. inch long, with large, rounded, terminal wing. 



TWIGS. Slender, pubescent, orange-brown, becoming gray- 

 brown. Winter buds: V4 inch long, characteristically long, con- 

 ical, sharp-pointed, lustrous, brown. 



BARK. Smooth, gray-brown and with resin blisters on young 

 trees; becoming very thick (6-24 inches), rough, with red- 

 brown ridges separated by deep furrows. 



WOOD. Highly variable from yellowish, narrow-ringed, 

 moderately light and soft, to red-brown, wide-ringed, with 

 weak spring wood and very dense summer wood. This tree 

 produces more timber than any other species. 



SILVICAL CHARACTERS. Intermediate in tolerance; re- 

 production abundant and vigorous; well developed, wide- 

 spreading lateral root system; attaining great age. 



HABITAT. Sea level to 11,000 feet; adapted to variety of 

 soils but best on moist, deep, porous soils of northern exposure; 

 will endure considerable drought; in pure stands or mixed 

 with Rocky Mountain conifers. 



GENERAL. The check list assigns Douglas-fir the name P. 

 menziesii; this author believes this was unwise and maintains the 

 name P. taxifolia. European taxonomists have separated this species 

 into 11 species; however this view is not commonly accepted in 

 North America. The Rocky Mountain form is recognized as the 

 separate geographical variety glauca (Mayr) Sudw. 



The bigcone Douglas-fir Pseudotsuga macrocarpa (Vasey) Mayr, 

 of Southern California is distinguished by its larger fruit (4— 

 ^Yz inches long) with bracts only slightly longer than the thick, 

 stiff cone scales. 



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