Pinus strobiformis

Trees to 30m; trunk to 0.9m diam., slender, straight; crown conic, becoming rounded to irregular. Bark gray, aging redbrown, furrowed, with narrow, irregular, scaly ridges. Branches spreading-ascending; twigs slender, pale redbrown, puberulous or glabrous, sometimes glaucous, aging gray or gray-brown, smooth. Buds ellipsoid, redbrown, ca. 1cm, resinous. Leaves 5 per fascicle, spreading to ascending-upcurved, persisting 3–5 years, 4–9cm × 0.6–1mm, straight, slightly twisted, pliant, dark green to blue-green, abaxial surface without evident stomatal lines, adaxial surfaces conspicuously whitened by narrow stomatal lines, margins sharp, razorlike and entire to finely serrulate, apex narrowly acute to short-subulate; sheath 1.5–2cm, shed early. Pollen cones cylindric, ca. 6–10mm, pale yellowbrown. Seed-cones maturing in 2 years, shedding seeds and falling soon thereafter, pendent, symmetric, lance-cylindric before opening, broadly lance-cylindric when open, 15–25cm, creamy brown to light yellowbrown, stalks to 6cm; apophyses somewhat thickened, strongly cross-keeled, tip reflexed; umbo terminal, low. Seeds ovoid; body 10–13mm, redbrown, essentially wingless. 2n =24.

Habitat: Arid to moist summit elevations, montane forests
Elevation: 1900–3000m

Ariz., N.Mex., Tex., n Mexico

Discussion

In the northern part of the range, Pinus strobiformis overlaps P. flexilis and reportedly hybridizes with it. On average P. strobiformis has longer, more slender leaves and thinner, more spreading-tipped apophyses than are found in P. flexilis, and stomatal bands are not evident on the abaxial surface of its leaves.

Selected References

None.

Lower Taxa