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Chihuahua white pine, Mexican white pine, pino enano, Southwestern white pine

slash pine

Habit Trees to 30m; trunk to 0.9m diam., slender, straight; crown conic, becoming rounded to irregular. Trees to 30m; trunk to 0.8m diam., straight to contorted; crown conic, becoming rounded or flattened.
Bark

gray, aging red-brown, furrowed, with narrow, irregular, scaly ridges.

orange- to purple-brown, irregularly furrowed and cross-checked into large, irregularly rectangular, papery-scaly plates.

Branches

spreading-ascending;

twigs slender, pale red-brown, puberulous or glabrous, sometimes glaucous, aging gray or gray-brown, smooth.

spreading to ascending;

twigs stout (to ca. 1cm thick), orange-brown, aging darker brown, rough-scaly.

Buds

ellipsoid, red-brown, ca. 1cm, resinous.

cylindric, silvery brown, 1.5–2cm;

scale margins fringed.

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.

2 or 3 per fascicle, spreading or ascending, persisting ca. 2 years, 15–20(–23)cm × 1.2–1.5mm, straight, slightly twisted, pliant, yellow- to blue-green, all surfaces with stomatal lines, margins finely serrulate, apex abruptly acute to acuminate;

sheath 1–2cm, base persistent.

Pollen cones

cylindric, ca. 6–10mm, pale yellow-brown.

cylindric, 30–40mm, purplish.

Seed(s)

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, falling the year after seed-shed, single or in pairs, symmetric, lance-ovoid before opening, ovoid or ovoid-cylindric when open, (7–)9–18(–20)cm, light chocolate brown, on stalks to 3cm;

apophyses lustrous (as if varnished), slightly raised, strongly cross-keeled;

umbo central, depressed-pyramidal, with short, stout prickle.

2n

=24.

Pinus strobiformis

Pinus elliottii

Habitat Arid to moist summit elevations, montane forests
Elevation 1900–3000m (6200–9800ft)
Distribution
from FNA
AZ; NM; TX; n Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; FL; GA; LA; MS; SC [Introduced in subtropical and warm temperate areas worldwide]
[WildflowerSearch map]
[BONAP county map]
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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Varieties 2 (native only in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Seedlings essentially without grass stage, buds thus scattered on the stem; leaves mostly in 3s, sometimes in 2s on same shoot; resin canals 3-5 per leaf; base of open cone ± truncate.
var. elliottii
1. Seedlings tending toward a grass stage, buds thus crowded on contracted stems; leaves mostly in 2s, sometimes in 3s on same shoot; resin canals 3-9 per leaf; base of open cone rounded.
var. densa
Source FNA vol. 2. FNA vol. 2.
Parent taxa Pinaceae > Pinus Pinaceae > Pinus
Sibling taxa
P. albicaulis, P. aristata, P. attenuata, P. balfouriana, P. banksiana, P. cembroides, P. clausa, P. contorta, P. coulteri, P. echinata, P. edulis, P. elliottii, P. engelmannii, P. flexilis, P. glabra, P. jeffreyi, P. lambertiana, P. leiophylla, P. longaeva, P. monophylla, P. monticola, P. muricata, P. palustris, P. ponderosa, P. pungens, P. quadrifolia, P. radiata, P. resinosa, P. rigida, P. sabiniana, P. serotina, P. strobus, P. sylvestris, P. taeda, P. torreyana, P. virginiana, P. washoensis
P. albicaulis, P. aristata, P. attenuata, P. balfouriana, P. banksiana, P. cembroides, P. clausa, P. contorta, P. coulteri, P. echinata, P. edulis, P. engelmannii, P. flexilis, P. glabra, P. jeffreyi, P. lambertiana, P. leiophylla, P. longaeva, P. monophylla, P. monticola, P. muricata, P. palustris, P. ponderosa, P. pungens, P. quadrifolia, P. radiata, P. resinosa, P. rigida, P. sabiniana, P. serotina, P. strobiformis, P. strobus, P. sylvestris, P. taeda, P. torreyana, P. virginiana, P. washoensis
Subordinate taxa
P. elliottii var. densa, P. elliottii var. elliottii
Synonyms P. ayacahuite var. brachyptera, P. ayacahuite var. reflexa, P. ayacahuite var. strobiformis, P. flexilis var. reflexa, P. reflexa P. heterophylla, P. taeda var. heterophylla
Name authority Engelmann: in Wislizenus, Mem. Tour N. Mexico 102. (1848) Engelmann: Trans. Acad. Sci. St. Louis 4: 186, plates 1–3. (1880)
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