Tree in habitat; north of Del Rio, Texas [Jeff Bisbee, 2014.09].
Foliage on a tree north of Del Rio, Texas [Jeff Bisbee, 2014.09].
Bark on a tree in the range of golden-cheeked warblers: iNaturalist observation 100234664 [v4rachel, 2021.11.02]
Tree in habitat; north of Del Rio, Texas [Jeff Bisbee, 2014.09].
Foliage on a tree north of Del Rio, Texas [Jeff Bisbee, 2014.09].
Bark on a tree in the range of golden-cheeked warblers: iNaturalist observation 100234664 [v4rachel, 2021.11.02]
Juniperus ashei
Ashe juniper, mountain cedar (Adams 1993), post cedar, rock cedar, Ozark white cedar, Mexican juniper (Farjon 2005).
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.
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).
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.
Map of the the distribution of Juniperus ashei, based on GBIF Occurrence Download https://doi.org/10.15468/dl.ak2aq4, retrieved 2023.08.06; data limited to occurrences with coordinate uncertainty <10 km and trimmed to eliminate extralimital occurrences, likely misidentifications, and location duplicates within a nearest-neighbor distance of 1 km.
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).
The white fungus often seen on the bark is the ascomycete Robergea albicedrae, which also grows on foliage, and for which J. ashei is the only known host. On young trees it grows on the trunk and major branches, but on older trees it’s usually confined to twigs. Although the fungus seems to be parasitic, there is evidence of more complex ecological relationships between the two species (Bernardin 2019).
J. ashei also provides essential habitat for the endangered golden-cheeked warbler Setophaga chrysoparia. The warbler builds its nests from juniper bark, and nests and forages in woodlands of mature juniper. According to the U.S. Fish and Wildlife Service (2019), "This bird requires older growth forest with a denser tree canopy where they forage for a variety of insects, including caterpillars... Although nests have been found in various trees, the one factor they have in common is the presence of strips of juniper bark. Once juniper reaches an advanced age, strips are easily taken from the bark and used in nest building. It appears that female golden-cheeked warblers are unable to build nests without this resource, which makes the presence of old-growth Ashe juniper vital to the species’ survival. ... Habitat loss or degradation is the main reason the golden-cheeked warbler is endangered. The clearing of old juniper woodlands for livestock grazing and urban expansion has decreased the area available for nesting. When large tracts of woods are broken up with pastures, roads and development, a population increase among nest predators such as the blue jays and the brown-headed cowbird occurs. The quantity of woodlands on the small fragmented tracts often means adults cannot find enough food to feed the young, or the young have no areas on which to disperse."
The largest tree has dbh 112 cm, height 13.4 m, and crown spread 14.9 m when last measured in 2018; it grows near Comal, Texas. This tree represents var. ovata (American Forests 2021).
The wood is sometimes used for fenceposts. The wood is steam-distilled to produce Texas cedarwood oil, a pleasant fragrance used in soaps, candles and cosmetics (Adams 2008a).
No data as of 2023.02.21.
The epithet honors botanist W. W. Ashe, who collected the type specimen.
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.
Adams, Robert P. 1993. Juniperus. Flora of North America Editorial Committee (eds.): Flora of North America North of Mexico, Vol. 2. Oxford University Press. This document is available online. Go to http://www.efloras.org, click on "Flora of North America," and search for "Juniperus."
Adams, Robert P. 2008a. Junipers of the World: The Genus Juniperus. Second edition. Trafford Publishing. Brief versions of the descriptions are available online at Adam's website, www.juniperus.org.
Adams, Robert P. 2008b. Distribution of Juniperus ashei var. ashei and var. ovata around New Braunfels, Texas. Phytologia 90(1):97-102.
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]
American Forests 2021. 2021 National Register of Champion Trees. Washington, DC: American Forests.
Bernardin, J. R. 2019. A morphological and molecular reassessment of Robergea albicedrae (Ascomycota). Thesis, Texas State University. Available, accessed 2021.11.08.
Buchholz, J. T. 1930. The Ozark white cedar. The Botanical Gazette (Crawfordsville, Indiana) 90(3):326-332.
U.S. Fish and Wildlife Service. 2019.02.15. Golden-Cheeked Warbler, https://www.fws.gov/refuge/Balcones_Canyonlands/GCW.html, accessed 2021.11.08, now defunct.
Last Modified 2023-08-06
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