Trees to 14m; trunk to 0.5m diam., strongly tapering, much branched; crown usually rounded, dense. Bark red-brown, irregularly furrowed or cross-checked, scaly. Branches spreading and ascending, persistent to near trunk base; twigs stout, orange-brown, aging brown to gray, sometimes sparsely puberulent. Buds ellipsoid, light red-brown, 0.5--0.7cm, resinous; scale margins fringed. Leaves 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 ellipsoid, ca. 10mm, yellow. Seed 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. Seeds cylindric-ellipsoid; body 15--20mm, gray-brown to brown, wingless. 2 n =24.

Dry low-montane or foothill pinyon-juniper woodland; 1000--2300m; Ariz., Calif., Idaho, Nev., Utah; Mexico in Baja California.

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

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

Common Name: singleleaf pinyon

Duration: Perennial

Nativity: Native

Lifeform: Tree

General: Trees generally 10-15 m tall, trunk 0.5 m in diameter, strongly tapering, with a rounded crown that is dense; bark red-brown, irregularly furrowed, broken into thin scales, upper part smooth, thin.

Needles: Usually solitary, rarely 2 per fascicle, 4-6 cm long, 1.3-2 mm, curved, terete and often 2-grooved, they are gray-green and all surfaces have stomatal lines, margins entire, persisting 4-6 years; sheath 0.5-1 cm, scales soon recurved, forming rosette, shed early.

Cones: Globose, symmetrical, 5-8 cm long, 6-7 cm widen when open, borne on very short peduncle that falls with cone; pale yellow-brown, with a small deciduous prickle.

Seeds: Highly productive, dark brown, about 15 mm long, wingless, with a very thin seed coat, 0.1-0.3 mm thick.

Ecology: Found in dry woodlands from 3,500-7,500 ft (106-2286 m).

Notes: The development of the single needle has been hypothesized as the consequence of increasing aridity, but this has never been fully borne out nor accepted. It is notable that it is present in those areas that are distinctly more arid. Probably not present in the southern part of Arizona, due in part to its known distribution to the north and northwest into the Great Basin.

Ethnobotany: The seeds were widely used for food, also used for firewood, building material, for cuts, as a disinfectant, for muscle soreness, for nausea, rheumatism, colds, fevers, indigestion, influenza, pneumonia, venereal diseases, sciatica, as a chewing gum, for sealing baskets and jugs, and even used to make baskets.

Etymology: Pinus is the ancient Latin name for pines, while monophylla means single leaved.

Synonyms: None

Editor: SBuckley, 2010