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photograph

At left, P. arizonica var. arizonica along Mex-16 near the Chihuahua-Sonora border. At right, P. leiophylla var. chihuahuana [C.J. Earle, 2007.02.08].

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Cones in situ (one missing) from a tree in the Sierra Madre Occidental, Sonora [C.J. Earle, 2007.02.08].

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Bark on a tree in the Sierra Madre Occidental, Sonora [C.J. Earle, 2007.02.08].

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Terminal bud [C.J. Earle, 2007.02.08].

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Sapling 2.5 m tall, in the Sierra Madre Occidental, Sonora [C.J. Earle, 2007.02.08].

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Foliar unit [C.J. Earle, 2007.02.08].

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Stand near the Chihuahua-Sonora border; the two large trees are each approx. 30 cm DBH [C.J. Earle, 2007.02.08].

 

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Conservation status
(not assessed)

Pinus arizonica var. arizonica

Common names

Arizona pine; pino de Arizona [Spanish].

Taxonomic notes

Syn: Pinus ponderosa D. Douglas ex P. Lawson var. arizonica (Engelmann) Shaw 1909; P. ponderosa D. Douglas ex P. Lawson ssp. arizonica (Engelmann) Murray 1982. Type specimen collected in 1874 by J.T. Rothrock in the Santa Rita Mountains of Arizona (Farjon and Styles 1997).

Hybridization or introgression with P. ponderosa subsp. scopulorum has been described for the population in the Santa Catalina Mountains of Arizona; the ponderosas occur at higher elevations and the Arizona pines at lower, with introgression occurring in the zone of overlap (Epperson et al. 2001).

Description

Tree to 35 m tall. Leaves in fascicles of 3-4(-5), rigid to slightly lax, straight or slightly curved and twisted, (8-)10-20(-23) cm × 0.9-1.4(-1.6) mm. Stomata on all faces of leaves, in (3-)4-8 lines on the convex abaxial face and in (3-)4(-5) lines on each adaxial face (the abaxial number of lines proportional to width of leaf). Seed cones ovoid, often slightly curved, (4.5-)5-7 × 3.5-6 cm when open. Seeds obliquely ovoid, slightly flattened, 4-6 × 3-3.5 mm. Seed wings obliquely ovate, 12-15 × 4-6 mm. Pollen is dispersed in springtime, dependent on altitude and latitude (Farjon and Styles 1997).

There seems to be a cline in the number of leaves per fascicle, with trees having predominantly 3 leaves in Sonora, Chihuahua, and Coahuila, but 5 leaves in Durango. However, a number of exceptions have been collected (Farjon and Styles 1997).

Distribution and Ecology

United States: Arizona and New Mexico; Mexico: Chihuahua, Coahuila, Durango, Nuevo León, Sinaloa, Sonora, and Zacatecas. See Pinus arizonica for an interactive distribution map. Var. arizonica is primarily found in the Sierra Madre Occidental at (1300-)2000-2700(-3000) m elevation on various substrates, but grows best in valleys and on mesas with deep soil, in moderately dry to mesic forest. Annual precipitation is low to moderate, 700-900 mm, mostly falling during the winter months, with occasional light winter frosts or snowfall. The trees may form pure stands, but are more commonly mixed with Quercus spp., other pines (e.g., P. engelmannii, P. strobiformis), and occasionally Juniperus flaccida at lower or J. deppeana at higher elevations (Farjon and Styles 1997).

Big tree

The largest known tree and Arizona state champion is 38.7 m tall and 124 cm dbh (Robert Van Pelt e-mail 2004.02.04).

Oldest

Work by Barton et al. (2001), presumably using living trees, has identified fire events going back to 1610. Thus trees 400 years or older probably occur.

Dendrochronology

See the species account.

Ethnobotany

Observations

This species is fairly common along Mex-16 in the vicinity of Parque Nacional Cascada de Basaseachic, as fine a place to visit as you are likely to find. It is also reasonably common in the higher mountain ranges of southern Arizona, such as the Santa Catalina, Santa Rita, and Chiricahua Mountains.

Remarks

In Mexico, this species is one of many principal hosts for the dwarf mistletoe Arceuthobium vaginatum subsp. vaginatum and, in Durango, A. verticilliflorum; in Arizona, New Mexico, Chihuahua, and Sonora it is also a principal host of A. vaginatum subsp. cryptopodum (Hawksworth and Wiens 1996).

Citations

Barton, A.M., T.W. Swetnam, and C.H. Baisan. 2001. Arizona pine (Pinus arizonica) stand dynamics: local and regional factors in a fire-prone madrean gallery forest of Southeast Arizona, USA. Landscape Ecology 16(4): 351-369.

Epperson, B.K., F.W. Telewski, A.E. Plovanich-Jones, and J.E. Grimes. 2001. Clinal differentiation and putative hybridization in a contact zone of Pinus ponderosa and P. arizonica (Pinaceae). American Journal of Botany 88: 1052-1057. Available: http://www.amjbot.org/cgi/content/full/88/6/1052, accessed 2007.11.19.

Murray, E. 1982. Notae Spermatophytae. Kalmia 12:23.

See also

Last Modified 2014-03-16