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Conservation status

Juniperus ashei

Buchholz 1930

Common names

Ashe juniper, mountain cedar (Adams 1993), post cedar, rock cedar, Ozark white cedar, Mexican juniper (Farjon 2005).

Taxonomic notes

Synonymy (Adams 2008a):

Type locality Sylamore, Arkansas, where collected by W. W. Ashe (Adams 2008a).

There are two varieties, the type and J. ashei var. ovata R. P. Adams 2007.

Adams (1993) says that "reports of hybridization with J. virginiana and J. pinchotii have been refuted using numerous chemical and morphologic characters." Farjon (2005) expresses some doubt about this, and adds his opinion that J. ashei is "very similar to J. monosperma, and seems to be an eastern vicariant of it," asserting that these are two members of a "species complex" that includes J. ashei, J. pinchotii, J. monosperma, J. angosturana, and J. coahuilensis.

Description

Dioecious large shrub or small tree, 6-10(-15) m tall, usually single-stemmed for basal 1-3 m, up to 50 cm dbh. Branches long, spreading to ascending, forming an open to dense, irregular to rounded crown. Bark on small branches first pink turning gray and flaking; on trunk and large branches brown, weathering gray and exfoliating in thin strips; often the bark bears a gray-white fungus. Foliage branches numerous, irregular, not pendulous. Ultimate branchlets spreading to erect, stiff, 5-10(-20) × 0.9-1.3 mm, 4-sided in cross section (whip shoots occasionally 3-sided), covered with closely appressed leaves, persistent. Leaves on lateral branchlets variably green, scale-like, decurrent, (slightly) imbricate, rhombic, often keeled, acute, with finely denticulate margins, 1-2 × 0.8-1.2 mm, with stomata on the abaxial side limited to decurrent leaf base, on the adaxial surface in two bands; glands obscure, resembling a small pimple, terminating a single resin cavity, without exudate. Pollen cones numerous, terminal, solitary, subglobose to ovoid, 2-4 x 2 mm, yellow-green maturing to pink or light brown. Seed cones maturing in 1 year, terminal on straight short branchlets, young cones pink glaucous, maturing dark blue, globose to broadly ovoid, 6-10 mm, succulent and resinous, with 1-2(-3) seeds. Seeds broad ovoid, 4-6 x 3-4.5 mm, not flattened, lustrous yellow-brown to chestnut brown, with a lighter hilum. Cotyledons 2, juvenile leaves restricted to seedlings, decurrent, the free part 7-10 x 0.8-1.3 mm. 2n = 22 (Adams 1993, Farjon 2005, Adams 2008a).

The type variety has cones mostly 9 mm in diameter bearing one seed, while variety ovata has cones mostly 6 mm in diameter bearing two seeds (Adams 2008a).

Similar species: J. monosperma usually has only one seed per cone, and unlike J. ashei, does not coppice (Farjon 2005).

Distribution and Ecology

Mexico: Coahuila; USA: Arkansas, Missouri (Ozark Mts.), Oklahoma, Texas (Edwards Plateau); at (150-)600-1550 m elevation on limestone glades and bluffs, or along streambeds (Adams 1993). It is exceedingly abundant on the Edwards Plateau, with dense populations covering millions of acres, but the disjunct populations in the remainder of its range consist of largely pure stands that in most cases cover relatively small areas (Adams and Baker 2007). Grows sometimes with Juniperus pinchotii, Pinus remota, Quercus spp. Climate continental, with warm summers and cold winters (Farjon 2005).

Hardy to Zone 7 (cold hardiness limit between -17.7°C and -12.2°C) (Bannister and Neuner 2001). See also Thompson et al. 1999.

Distribution data from USGS (1999). Points plotted as tree icons represent isolated or approximate locations.

Var. ovata primarily occurs in Coahuila and in Texas west of approximately 101.2°W, while the type variety predominates in the remainder of the species' range (Adams 2008a).

Big tree

Diameter 93 cm, height 12 m, crown spread 11 m, located near the junction of Madeline St. and Cedar Elm St. in New Braunfels, TX. This tree represents var. ovata (American Forests 1996; Adams 2008a, 2008b).

Oldest

Dendrochronology

Ethnobotany

Sometimes used as fenceposts. The wood is steam-distilled to produce Texas cedarwood oil, a pleasant fragrance used in soaps, candles and cosmetics (Adams 2008a).

Observations

Remarks

Adams and Baker (2007) present an interesting argument that var. ovata formerly represented the only variety of this species, occurring in west Texas refugia during the last glacial maximum, with the type variety evolving during Holocene radiation of the species into its current range.

Citations

Adams, R. P. and L. Baker. 2007. Pleistocene infraspecific evolution in Juniperus ashei Buch. Phytologia 89(1):8-23. [includes description of J. ashei var. ovata]

Adams, R. P. 2008b. Distribution of Juniperus ashei var. ashei and var. ovata around New Braunfels, Texas. Phytologia 90(1):97-102.

Buchholz, J. T. 1930. The Ozark white cedar. The Botanical Gazette (Crawfordsville, Indiana) 90(3):326-332.

See also

Last Modified 2012-11-28