Juniperus scopulorum
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 Juniperus scopulorum in North Dakota
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| Juniperus scopulorum Sarg. |
Juniperus scopulorum (Rocky Mountain Juniper) is a species of juniper native to western North America, in Canada in British Columbia and southwest Alberta, in the United States from Washington east to North Dakota, south to Arizona and also locally western Texas, and northernmost Mexico from Sonora east to Coahuila. It grows at altitudes of 500-2,700 m on dry soils, often together with other juniper species.[2][3][4][5]
It is a small tree reaching 5-15 m (rarely to 20 m) tall, with a trunk up to 1 m (rarely 2 m) diameter. The shoots are slender, 0.7-1.2 mm diameter. The leaves are arranged in opposite decussate pairs, or occasionally in whorls of three; the adult leaves are scale-like, 1-2 mm long (to 5 mm on lead shoots) and 1-1.5 mm broad. The juvenile leaves (on young seedlings only) are needle-like, 5-10 mm long. The seed cones are berry-like, globose to bilobed, 6-9 mm in diameter, dark blue with a pale blue-white waxy bloom, and contain two seeds (rarely one or three); they are mature in about 18 months. The pollen cones are 2-4 mm long, and shed their pollen in early spring. It is dioecious, producing cones of only one sex on each tree.[2][3][5]
One particular specimen, the "Jardine Juniper" in Utah, is thought to be over 1500 years old,[6] while a dead trunk found in New Mexico was found to have 1,888 rings; older trees in the same area are suspected to exceed 2,000 years.[4]
It is closely related to Juniperus virginiana, and often hybridizes with it where their ranges meet on the Great Plains. Hybrids with Juniperus horizontalis also occur.
An isolated population of junipers occurs close to sea level in the Puget Sound area and southeastern Vancouver Island. Previously included in J. scopulorum, it has recently been shown to be genetically distinct, and has been described as a new species Juniperus maritima. It is a cryptic species barely distinguishable on morphology, though it does differ in phenology, with the cones maturing in 14–16 months, and often has the tips of the seeds exposed at the cone apex.[7]
[edit] Uses
The cultivar 'Skyrocket' is a very popular ornamental plant in gardens, grown for its very slender, strictly erect growth habit. Several other cultivars are also grown to a lesser extent.
[edit] References
- ^ Conifer Specialist Group (1998). Juniperus scopulorum. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
- ^ a b Farjon, A. (2005). Monograph of Cupressaceae and Sciadopitys. Royal Botanic Gardens, Kew. ISBN 1-84246-068-4
- ^ a b Adams, R. P. (2004). Junipers of the World. Trafford. ISBN 1-4120-4250-X
- ^ a b Gymnosperm Database: Juniperus scopulorum
- ^ a b Flora of North America: Juniperus scopulorum
- ^ Utahlink: Jardine Juniper
- ^ Adams, R. P. (2007). Juniperus maritima, the seaside juniper, a new species from Puget Sounds, North America. Phytologia 89 (3): 263-283. Available online (pdf file).
