Like several other junipers, Creeping Juniper (Juniper horizontalis) is a prostrate (sprawling) woody plant that grows mainly along the ground rather than vertically. The creeping branches produce short erect branchlets with scale-like leaves. The leaves are green, but turn redddish purple in winter. The seed cones, which generally mature in two years, are of two distinct sizes and contain several seeds each.
Creeping Juniper is distributed across much of Canada and, more locally, across the northern tier of the adjacent United States. It is found on sand dunes, sandy and gravelly soils, prairies, slopes, rock outcrops, and streambanks from 0 to 1000 m elevation.
At the margins of its range, this prostrate species apparently hybridizes with two closely related species, the trees Eastern Red Cedar (J. virginiana) and Rocky Mountain Juniper (J. scopulorum), where their ranges overlap with Creeping Juniper. Creeping Juniper has sometimes been treated as a prostrate form of J. virginiana.
(Fassett 1945; Adams 1983; Palma-Otal et al. 1983; Adams 2011 and references therein)
- Adams, R.P 1983. Infraspecific terpenoid variation in Juniperus scopulorum: Evidence for Pleistocene refugia and recolonization in western North America. Taxon 32: 30-46.
- Adams, R.P. 2011. Junipers of the World: The Genus Juniperus, 3rd Edition. Trafford Publishing.
- Fassett, N.C. 1945. Juniperus virginiana, J. horizontalis, and J. scopulorum. V. Taxonomic treatment. Bulletin of the Torrey Botanical Club 72: 480-482.
- Palma-Otal, M., W.S. Moore, R.P. Adams, and G.R. Joswiak. 1983. Morphological. chemical, and biogeographical analyses of a hybrid zone involving Juniperus virginiana and J. horizontalis in Wisconsin.Canadian Journal of Botany 61(10): 2733-2746.