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Two saplings growing in Yellowstone Natl. Park. Despite growing under almost identical conditions, one is bright green and the other extremely glaucous, illustrating how glaucousness can be almost independent of environment [C.J. Earle, 2002.08.05].

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Conservation status

Juniperus scopulorum

Sargent 1897

Common names

Rocky Mountain juniper, mountain red cedar, weeping juniper (Peattie 1950), Rocky Mountain redcedar (Adams 1993).

Taxonomic notes

Syn: Sabina scopulorum (Sargent) Rydberg (Adams 1993). Distribution contiguous with and morphology very similar to J. virginiana. J. scopulorum hybridizes with J. virginiana "in zones of contact in the Missouri River basin and with J. horizontalis (J. × fassettii Boivin; Fassett 1945). Relictual hybridization with J. virginiana is known in the Texas panhandle" (Adams 1993).

The occurrence of this species in the Puget Sound area was long noted by local botanists as a curiosity and as an illustration of the unusual aridity to be found in parts of western Washington situated in the rain shadow of the Olympic Mountains. That will have to change now, as the Puget Sound region populations have recently (Adams 2007) been described as a distinct species, Juniperus maritima. Other closely related species (all of which have a very similar appearance) include the Caribbean species J. barbadensis, J. bermudiana, J. gracilior, J. lucayana and J. saxicola, and the Mexican species J. blancoi and J. mucronata. All of these, however, are very rare.

Description

"Trees dioecious, to 20 m, single-stemmed (rarely multistemmed); crown conic to occasionally rounded. Bark brown, exfoliating in thin strips, that of small branchlets (5-10 mm diam.) smooth, that of larger branchlets exfoliating in plates. Branches spreading to ascending; branchlets erect to flaccid, 3-4-sided in cross section, ca. 2/3 or less as wide as length of scalelike leaves. Leaves light to dark green but often glaucous blue or blue-gray, abaxial gland elliptic, conspicuous, exudate absent, margins entire (at 20× and 40×); whip leaves 3-6 mm, not glaucous adaxially; scalelike leaves 1-3 mm, not overlapping to overlapping by not more than 1/5 their length, keeled to rounded, apex obtuse to acute, appressed or spreading. Seed cones maturing in 2 years, of 2 distinct sizes, generally with straight peduncles, globose to 2-lobed, 6-9 mm, appearing light blue when heavily glaucous, but dark blue-black beneath glaucous coating when mature (or tan beneath glaucous coating when immature), resinous to fibrous, with (1)2(3) seeds. Seeds 4-5 mm. 2n = 22" (Adams 1993).

Distribution and Ecology

Canada, USA and Mexico; British Columbia (Vancouver Is. to the Rockies), Alberta (rare), S in Rockies through Montana, Wyoming, Colorado and New Mexico to W Texas, S-C Arizona and N Mexico; also in Washington, E Oregon, E Nevada and Utah; also on mountains E of the Rocky Mountain Front in Montana, North Dakota, South Dakota and Nebraska (Peattie 1950). Found at 0-2700 m elevation, mostly on rocky soils (Adams 1993). See also Thompson et al. (1999). Hardy to Zone 3 (cold hardiness limit between -39.9°C and -34.4°C) (Bannister and Neuner 2001).

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

Big tree

Diameter 200 cm, height 12 m, crown spread 6 m, located in Cache National Forest, Utah (American Forests 1996).

Oldest

A log (specimen CRE 175) with crossdated inner date 29 BC and outer date AD 1859 was collected in July 1993 by Henri Grissino-Mayer, James Riser, Rex Adams, and Ikuo Furukawa. This indicates that the tree lived for more than 1888 years. The specimen is from El Malpais National Monument in New Mexico, an area where all native conifer species attain exceptional ages. Grissino-Mayer reports (pers. comm., January 1997) that "at El Malpais National Monument, we believe that there exist some 2000+ year old JUSCs as well."

Dendrochronology

Ethnobotany

Observations

This species is common throughout most of its range, and in much of the Rocky Mountains is the only juniper (or at least the only one in section Sabina), which makes identification relatively easy. However, I have not seen any particularly extraordinary stands.

Remarks

Citations

See also

Burns & Honkala 1990.

Elias 1987.

Farjon (2005) provides a detailed account, with illustrations.

Lanner 1983.

Little 1980.

Last Modified 2014-12-05