Trees to 26m; trunk to 2m diam., straight to contorted; crown conic, becoming rounded. Bark gray, nearly smooth, cross-checked in age into scaly plates and ridges. Branches spreading to ascending, often persistent to trunk base; twigs pale red-brown, puberulous (rarely glabrous), slightly resinous, aging gray, smooth. Buds ovoid, light red-brown, 0.9--1cm, resinous; lower scales ciliolate along margins. Leaves 5 per fascicle, spreading to upcurved and ascending, persisting 5--6 years, 3--7cm ´ 1--1.5mm, pliant, dark green, abaxial surface with less conspicuous stomatal bands than adaxial surfaces, adaxial surfaces with strong, pale stomatal bands, margins finely serrulate, apex conic-acute to acuminate; sheath 1--1.5(--2)cm, shed early. Pollen cones broadly ellipsoid-cylindric, ca. 15mm, pale red or yellow. Seed cones maturing in 2 years, shedding seeds and falling soon thereafter, spreading, symmetric, lance-ovoid before opening, cylindro-ovoid when open, 7--15cm, straw-colored, resinous, sessile to short-stalked, apophyses much thickened, strongly cross-keeled, umbo terminal, depressed. Seeds irregularly obovoid; body 10--15mm, brown, sometimes mottled darker, wingless or nearly so. 2 n =24.
High montane forests, often at timberline; (1000--)1500--3600m; Alta., B.C.; Ariz., Calif., Colo., Idaho, Mont., Nebr., Nev., N.Mex., N.Dak., Oreg., S.Dak., Utah, Wyo.
Pinus flexilis , much branched with a strongly tapering trunk, is little utilized because of its form and relative inaccessibility. It reportedly forms intermediates with P . strobiformis where the two overlap. The fresh-cut wood has the odor of turpentine.