Pinus strobiformis
Pinus rigida
Chihuahua white pine, Mexican white pine, pino enano, Southwestern white pine
pin rigide, pitch pine
gray, aging red-brown, furrowed, with narrow, irregular, scaly ridges.
red-brown, deeply and irregularly furrowed, with long, irregularly rectangular, flat, scaly ridges, resin pockets absent.
spreading-ascending;
twigs slender, pale red-brown, puberulous or glabrous, sometimes glaucous, aging gray or gray-brown, smooth.
arching-spreading to ascending, poorly self-pruning; 2-year-old branchlets stout (mostly over 5mm thick), orange-brown, aging darker brown, rough.
ellipsoid, red-brown, ca. 1cm, resinous.
ovoid to ovoid-cylindric, red-brown, ca. 1–1.5cm, resinous;
scale margins fringed, apex cuspidate.
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.
3(–5) per fascicle, spreading to ascending, persisting 2–3 years, 5–10(–15)cm × 1–1.5(–2)mm, straight, twisted, deep to pale yellow-green, all surfaces with fine stomatal lines, margins serrulate, apex abruptly subulate-acuminate;
sheath 0.9–1.2cm, base persistent.
cylindric, ca. 6–10mm, pale yellow-brown.
cylindric, ca. 20mm, yellow.
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 yellow-brown, stalks to 6cm;
apophyses somewhat thickened, strongly cross-keeled, tip reflexed;
umbo terminal, low.
cones maturing in 2 years, shedding seeds soon thereafter or variously serotinous and long-persistent, often clustered, symmetric, conic to ovoid before opening, broadly ovoid with flat or slightly convex base when open, 3–9cm, creamy brown to light red-brown, sessile to short-stalked, base truncate, scales firm, with dark red-brown border on adaxial surface distally;
apophyses slightly raised, rhombic, with strong transverse keels;
umbo central, low-triangular, with slender, downcurved prickle.
=24.
=24.
Pinus strobiformis
Pinus rigida
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Pinus rigida often has poor form and is not valued highly as saw timber. It is fire successional, sprouts adventitiously, and is frequently shrubby in the northern part of its range. It is known to hybridize naturally with P. echinata.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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