Gymnosperm Database
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Conservation status

Juniperus horizontalis

Moench 1794

Common names

Creeping juniper, savinier, genévrier horizontal (Adams 1993), Bar Harbor juniper in Maine (V. Dinets, e-mail 18-Oct-2003).

Taxonomic notes

Syn: J. communis var. jackii (Silba 1986); Juniperus horizontalis var. douglasii hort.; J. horizontalis var. variegata Beissner. "Juniperus horizontalis, a prostrate species, hybridizes with the trees J. virginiana and J. scopulorum (Adams 1983; Fassett 1945; Palma-Otal et al. 1983) and is closely related to both. The hybrid between J. horizontalis and J. scopulorum has been named J. × fassettii Boivin" (Adams 1993).

Description

"Shrubs dioecious, prostrate to decumbent; crown depressed. Bark brown, exfoliating in thin strips, that of small branchlets (5-10 mm diam.) smooth, that of larger branchlets exfoliating in wide strips or plates. Branches creeping; branchlets erect, 3-4-sided in cross section, ca. 2/3 or less as wide as length of scalelike leaves. Leaves green but turning reddish purple in winter, abaxial gland elliptic, conspicuous, exudate absent, margins entire (at 20× and 40×); whip leaves 4-8 mm, not glaucous adaxially; scalelike leaves 1.5-2 mm, mostly overlapping to 1/3 their length, apex rounded or obtuse to acute and apiculate, spreading. Seed cones mostly maturing in 2 years, of 2 distinct sizes, generally with curved peduncles, globose to ovoid, 5-7 mm, blue-black to brownish blue when mature, lightly glaucous, soft and resinous, with 1-2(-3) seeds. Seeds 4-5 mm. 2n = 22" (Adams 1993).

Distribution and Ecology

Canada: all provinces and territories; France: St. Pierre and Miquelon; USA: Alaska, Montana, Wyoming, Nebraska, South Dakota, North Dakota, Minnesota, Iowa, Illinois, Wisconsin, Michigan, New York, Vermont, Massachusetts, New Hampshire and Maine; at 0-1000 m on sand dunes, sandy and gravelly soils, prairies, slopes, rock outcrops, and stream banks (Adams 1993). See also Thompson et al. 1999. Hardy to Zone 4 (cold hardiness limit between -34.3°C and -28.9°C) (Bannister and Neuner 2001).

Distribution data. Data sources (click on data points to view) include my observations (accompanied by a list of associated gymnosperm taxa), GBIF (2014; accompanied by name or abbreviation of the collecting institution), Tropicos (2014; accompanied by detailed specimen data), the New York Botanical Garden (2014; accompanied by detailed specimen data), and the Consortium of Pacific Northwest Herbaria (2014; accompanied by detailed specimen data).

Big tree

Oldest

Dendrochronology

Ethnobotany

Observations

Remarks

Citations

See also

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

Last Modified 2014-08-17