Pinus durangensis

Martínez 1942

Common names

Ocote, pino blanco, pino (Perry 1991).

Taxonomic notes

Syn: Pinus durangensis forma quinquefoliata Martínez 1948; Pinus martinezii E. Larsen 1964; Pinus douglasiana var. martinezii (E. Larsen) Silba 1990 (Farjon 1998). This species belongs to Pinus subsection Ponderosae; see the "Taxonomic notes" for Pinus ponderosa for further discussion.

Description

Trees with a single, straight, round bole 30-40 m tall and 50-80 cm dbh with a dense pyramidal crown that becomes more rounded and shallow with age, with drooping to horizontal branches. Bark dark brown, rough, longitudinally fissured into scaly plates. Branchlets thick, stiff, rough and scaly. Leaves 5-7(-8) per fascicle, 0.8-0.9 mm × 15-20 cm, stiff, erect, margins finely serrate, stomata on all surfaces, with 2-3(-4) medial resin canals. Fascicle sheaths 15-18 mm long, persistent, brown, scaly. Cones usually in groups of 2-3 on 5-8 mm peduncles (appearing sessile), 5-7 cm long. Cones mature in December and January and promptly open and disperse their seed, remaining on the tree for some months thereafter. When they fall, the peduncle and some few scales remain on the tree. Cone scales stiff, hard, the apophysis raised, subpyramidal, transversely keeled, slightly reflexed; with a dorsal, gray, raised umbo bearing a sharp, often recurved, persistent prickle. Seeds gray, 5-7 mm long with a 5-7×12-15 mm articulate wing. Wood light, soft, yellowish (Perry 1991).

Distribution and Ecology

Mexico: E Sonora, Chihuahua, Durango, Zacatecas, N Jalisco (common), and scattered S through Jalisco and Michoacán.

Distribution data from USGS (1999).

Its distribution is mainly through the N Sierra Madre Occidental, where it occurs at (1400-)1600-2800(-3000?) m elevation. Rainfall is about 600 mm per year in Durango; probably more like 1000 mm per year at the elevation where the pines are most abundant, falling mostly as rain but sometimes as snow. At the lower elevation limits it may be found with Juniperus deppeana and Pinus oocarpa; higher, it occurs in pure stands, in mixed pine forest with P. arizonica, P. leiophylla, or P. engelmannii as codominants, or in pine-oak forests. At the upper limits of its distribution it can be found with Hesperocyparis lusitanica and/or Abies [species not specified]. Other associated pines include P. montezumae, P. teocote, and in Michoacán, P. ayacahuite (Farjon and Styles 1997).

Hardy to Zone 8 (cold hardiness limit between -12.1°C and -6.7°C) (Bannister and Neuner 2001). See also Thompson et al. (1999).

Remarkable Specimens

Ethnobotany

This is one of Mexico's more important timber trees, and logging is a widespread and commercially important activity in its range. Perry (1991) reports that logging has greatly reduced its range. It is also locally used for firewood and carpentry.

Observations

Remarks

This species is a host to the dwarf mistletoes Arceuthobium abietinum f. sp. concoloris, A. globosum subsp. globosum, A. globosum subsp. grandicaule, A. rubrum, A. vaginatum subsp. vaginatum, A. vaginatum subsp. cryptopodum, A. verticilliflorum (only in Durango), and A. durangense, the latter having been described from a collection of this species 58 km W of El Salto on highway 40, the Durango-Mazatlan highway (Hawksworth and Wiens 1996). See the "Remarks" in Abies durangensis for a relevant story.

Citations

Martínez, M. 1942. Une nueva pínacea Méxicana. Anales Inst. Biol. Univ. Nac. México 13(1):23-29.

See also