PINACEAE 



PoNDEROSA Pine. Western Yellow Pine 

 Pinus ponder osa Laws. 



HABIT. A tree 150-180 feet high and 3-4 feet in diameter 

 (max. 232 by 8 feet on Pacific Coast); bole symmetrical, clear; 

 crown short, conical or flat-topped. 



LEAVES. In fascicles of 3, or 2 and 3 (rarely from 1-5); 

 3-11 inches long (mostly 4-7 inches); stout; dark to yellow- 

 green; persistent 2-7 years (usually 4-6 years); cross section 

 shows 2-5 resin ducts; basal sheath i4~M- inch long, persistent. 



FLOWERS. Male yellow; female red, clustered or paired. 



FRUIT, Subsessile; 2|/2~6 inches long; ovoid; open at maturity; 

 basal scales remaining attached to twig when cones shed; scales 

 thin, armed with short prickles. Seed: K inch long; brown- 

 purple, often mottled; wing 1 inch long. 



TWIGS. Stout; orange-colored; turpentine odor when bruised. 

 Winter buds: about Yz inch long; often resinous. 



BARK. Black and furrowed on young trees; on old trunks 

 2-4 inches thick; yellow-brown to cinnamon-red; in large, flat 

 plates. 



WOOD, Very important; rather light and soft; sapwood 

 very thick with properties of white pine ; heartwood light brown ; 

 uses include construction, planing mill products, ties, etc. 



SILVICAL CHARACTERS. Intolerant; growth slow; ma- 

 turity in 350-500 years (extreme age 660 years); reproduction 

 vigorous; long taproot; fire and bark beetles cause damage. 



HABITAT. Transition zone; large altitudinal range, from 

 2,000-8,000 feet; exceedingly drouth resistant; in open pure 

 stands or more commonly the most abundant tree in mixed 

 coniferous stands, 



GENERAL. The Rocky Mountain variety is designated P. 

 ponderosa var. scopulorum Engelm, Arizona pine, P. ponderosa var. 

 arizonica (Engelm.) Shaw, of southern New Mexico, Arizona, 

 and northern Mexico, diff"ers in having needles in fascicles of 

 5 and cones less than 3|/^ inches long. 



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