Juniperus horizontalis

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Juniperus horizontalis

Juniperus horizontalis, Pancake Bay sand dunes, Ontario, Canada

Conservation status

Least concern

Scientific classification

Kingdom:	Plantae
Division:	Pinophyta
Class:	Pinopsida
Order:	Pinales
Family:	Cupressaceae
Genus:	Juniperus
Species:	J. horizontalis

Binomial name

Juniperus horizontalis
Moench

Juniperus horizontalis (Creeping Juniper) is a low-growing shrubby juniper native to northern North America, throughout most of Canada from Yukon east to Newfoundland, and in the United States in Alaska, and locally from Montana east to Maine, reaching its furthest south in Wyoming and northern Illinois.

It lives up to both its scientific and common names, reaching only 10-30 cm tall but often spreading several metres wide. 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 8 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 cones are berry-like, globose to bilobed, 5-7 mm in diameter, dark blue with a pale blue-white waxy bloom, and contain two seeds (rarely one or three); they usually have a curved stem and are mature in about 18 months. The male cones are 2-4 mm long, and shed their pollen in early spring. It is dioecious, producing cones of only one sex on each plant.

Juniperus horizontalis 'Wiltonii' as a garden plant

It is closely related to Juniperus virginiana, and often hybridizes with it where their ranges meet in southern Canada. Hybrids with Juniperus scopulorum also occur.

Well over 100 different cultivars have been selected for use as ornamental plants in gardens, their strictly prostrate growth habit being valued for ground cover. Popular examples include 'Bar Harbor', 'Blue Acres', 'Emerald Spreader', 'Green Acres', and 'Wiltonii' ("Blue Rug Juniper"). Many of the most popular cultivars have strikingly glaucous foliage, while others are bright green, yellowish or variegated.