Pinus contorta

Shrubs or trees to 50m; trunk to 0.9m diam., straight to contorted; crown various according to genetic race. Bark brown to gray- or red-brown, platy to furrowed. Lower branches often descending, the upper spreading or ascending. Twigs slender, orange to red-brown, aging darker brown, rough. Buds narrowly to broadly ovoid, dark red-brown, to 1.2cm, slightly resinous. Leaves 2 per fascicle, spreading or ascending, persisting 3--8 years, 2--8cm ´ 0.7--2(--3)mm, twisted, yellow-green to dark green, all surfaces with fine stomatal lines, margins finely serrulate, apex blunt to acute or narrowly acuminate; sheath 0.3--0.6(--1)cm, persistent. Pollen cones ellipsoid to cylindric, 5--15mm, orange-red. Seed cones maturing in 2 years or variably serotinous, variably persistent, spreading to reflexed, often curved, nearly symmetric or variably asymmetric, lanceoloid to ovoid before opening, broadly ovoid to nearly globose when open, 2--6cm, tan to pale red-brown, lustrous, nearly sessile or on stalks to 1cm; apophyses nearly rhombic, variously elongate, cross-keeled, often mammillate toward outer cone base and on inside above middle; umbo central, depressed-triangular, prickle barely elongate to stubby or slender and to 6mm. Seeds compressed, obovoid; body ca. 5mm, red-brown, mottled with black, or all black; wing 10--14mm. 2 n =24 (variety not indicated).

Pinus contorta is fire successional over most of its range and is characterized by prolific seeding and high seed viability in disturbed habitats, often resulting in extremely slow-growing, overly dense stands. Some authors consider it to consist of 4 races; these have been given various infraspecific ranks, but perhaps they are more conventionally treated as 3 varieties.