Common Names

Chihuahua pine, ocote blanco, ocote chino, pino real (Elmore & Janish 1976).

Taxonomic notes

Syn: Pinus chihuahuana Engelmann 1848; P. leiophylla subsp. chihuahuana (Engelm.) E. Murray 1982 (Farjon 1998).

Description

Tree 10-15(-25) m tall and 20-60(-90) cm dbh, slender, with a single round trunk, often forked higher up; crown conic, becoming rounded. Bark brown to red-brown, narrowly furrowed, cross-checked into long, irregularly and narrowly rectangular, flat, scaly ridges. Branches ascending; twigs slender, orange-brown or glaucous and violet, aging red-brown, ±smooth or cracking. Buds ovoid, light red-brown, ca. 0.6-0.7(1) cm, slightly resinous. Leaves (2-)3(-4) per fascicle, spreading-ascending, persisting 2 years, (4-)6-12(-15) cm × 0.8-1.3(-1.5) mm, straight to slightly twisted, dull gray-green, with 5-8 lines of stomata on the convex abaxial face and 3-4 lines on each adaxial face, margins finely serrulate, apex acute to acuminate; sheath to 1.5 cm, shed early and completely. Resin canals 4-6, medial, sometimes 1-2 internal. Pollen cones broadly ellipsoid, ca. 10-15 mm, brown or yellow. Seed cones maturing in 3 years, shedding seeds soon thereafter but long-persistent, paired or solitary, symmetric, lateral, narrowly ovoid before opening, broadly ovoid to nearly globose when open, 3.5-5(9) cm, chestnut brown or greenish brown, aging gray to gray-brown, stalks to 1.5 cm; apophyses slightly thickened and raised, not keeled; umbo central, slightly raised or depressed, with short, often deciduous prickle or unarmed. Seeds obovoid; body ca. 2 mm, gray, mottled darker; wing ca. 10 mm, dark-lined. 2n=24 (Kral 1993, Farjon and Styles 1997).

It differs from variety leiophylla "in its dark, less roughened bark, its shorter range of leaf length, and its slightly broader leaves that occur more consistently in threes" (Kral 1993).

Range

USA: E central & SE Arizona, and SW New Mexico; Mexico: NE Sonora, W Chihuahua, Durango, Nayarit, N Jalisco, and Zacatecas, along the Sierra Madre Occidental at 1500-2700(-2950) m elevation. Where sympatric with var. leiophylla, it usually grows to lower elevations, where it may occur with other xerophytes including Pinus cembroides, Juniperus spp., Opuntia spp. and Arctostaphylos spp. At higher elevations, its habitat is usually on rocky ridges and mountain slopes with P. engelmannii and P. arizonica, and farther south, with a broad suite of Pinus and Quercus species (Farjon and Styles 1997).

Big Tree

As of 1998, the largest specimen in the United States was 26.5 m tall and 98 cm dbh, with a crown spread of 10.4 m, at Fort Apache Indian Reservation in Arizona (American Forests 2005). I have no data on big trees in Mexico.

Oldest

Dendrochronology

Ethnobotany

Observations

Easy to find at Cochise Head and Chiricahua National Monument, both in the Chiricahua Mountains of southeast Arizona.

Remarks

This species is a principal host for the dwarf mistletoes Arceuthobium gillii, A. nigrum, and A. yecorense (Hawksworth and Wiens 1996).

See Also

FEIS database (considerable detail on ecology; large bibliography).

Peattie 1950.

Perry 1991.