Pinus strobiformis
Pinus engelmannii
Chihuahua white pine, Mexican white pine, pino enano, Southwestern white pine
Apache pine, Arizona longleaf pine, pino real
gray, aging red-brown, furrowed, with narrow, irregular, scaly ridges.
dark brown, at maturity deeply furrowed, ridges becoming yellowish, of narrow, elongate, scaly plates.
spreading-ascending;
twigs slender, pale red-brown, puberulous or glabrous, sometimes glaucous, aging gray or gray-brown, smooth.
straight to ascending;
twigs stout (1–2cm thick), pale gray-brown, aging darker brown, rough.
ellipsoid, red-brown, ca. 1cm, resinous.
ovoid-conic, to 2cm, resinous;
scale margins pale fringed.
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-ascending, often drooping, forming a brush at twig tips, persisting 2 years, (20–)25–45cm × 2mm, dull green, all surfaces with fine stomatal lines, margins coarsely serrulate, apex conic-subulate;
sheath 3–4cm, base persistent.
cylindric, ca. 6–10mm, pale yellow-brown.
cylindric, ca. 25mm, yellow to yellow-brown.
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 and shedding seeds soon thereafter, not persistent, terminal, sometimes curved, often asymmetric, lance-ovoid before opening, ovoid when open, 11–14cm, light dull brown, nearly sessile or short-stalked;
apophyses rhombic, somewhat to quite elongate, strongly raised toward outer cone base, sometimes curved, strongly cross-keeled, narrowed to thick, curved, broadly triangular-based umbo, this often producing outcurved claw.
=24.
=24.
Pinus strobiformis
Pinus engelmannii
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.)
In general appearance Pinus engelmannii much resembles P. palustris with its short-persistent, long leaves (but in this species drooping) and in its tendency to form a grass stage. It has a deep taproot as do P. palustris and P. ponderosa.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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