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

piñón, single leaf pinyon, single-leaf pine, singleleaf pinyon pine

Habit Trees to 30m; trunk to 0.9m diam., slender, straight; crown conic, becoming rounded to irregular. Trees to 14m; trunk to 0.5m diam., strongly tapering, much branched; crown usually rounded, dense.
Bark

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

red-brown, irregularly furrowed or cross-checked, scaly.

Branches

spreading-ascending;

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

spreading and ascending, persistent to near trunk base;

twigs stout, orange-brown, aging brown to gray, sometimes sparsely puberulent.

Buds

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

ellipsoid, light red-brown, 0.5–0.7cm, resinous;

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.

1(–2) per fascicle, ascending, persisting 4–6(–10) years, 2–6cm × 1.3–2(–2.5)mm, curved, terete (though often 2-grooved), gray-green, all surfaces with stomatal lines, margins entire, apex subulate;

sheath 0.5–1cm, scales soon recurved, forming rosette, shed early.

Pollen cones

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

ellipsoid, ca. 10mm, yellow.

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, shedding seeds and falling soon thereafter, spreading, symmetric, ovoid before opening, broadly depressed-ovoid to nearly globose when open, 4–6(–8)cm, pale yellow-brown, nearly sessile;

apophyses thickened, slightly raised;

umbo subcentral, raised or depressed, nearly truncate, apiculate.

2n

=24.

=24.

Pinus strobiformis

Pinus monophylla

Habitat Arid to moist summit elevations, montane forests Dry low-montane or foothill pinyon-juniper woodland
Elevation 1900–3000m (6200–9800ft) 1000–2300m (3300–7500ft)
Distribution
from FNA
AZ; NM; TX; n Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; ID; NV; UT; Mexico in Baja California
[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.)

Pinus monophylla hybridizes with P. edulis and P. quadrifolia.

Singleleaf pinyon (Pinus monophylla) is the state tree of Nevada.

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

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. elliottii, P. engelmannii, P. flexilis, P. glabra, P. jeffreyi, P. lambertiana, P. leiophylla, P. longaeva, 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
Synonyms P. ayacahuite var. brachyptera, P. ayacahuite var. reflexa, P. ayacahuite var. strobiformis, P. flexilis var. reflexa, P. reflexa Caryopitys monophylla, P. californiarum, P. cembroides var. monophylla
Name authority Engelmann: in Wislizenus, Mem. Tour N. Mexico 102. (1848) Torrey & Frémont: in Frémont, Rep. Exped. Rocky Mts. 2: 319, plate 4. (1845)
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