Juniperus horizontalis

Living up to both its scientific and common names, the species reaches only 10–30 centimetres (3+7⁄8–11+3⁄4 in) tall but often spreading several metres wide. The shoots are slender, 0.7–1.2 millimetres (1⁄32–1⁄16 in) diameter. The leaves are arranged in opposite decussate pairs, or occasionally in whorls of three; the adult leaf blades are scale-like, 1–2 mm long (to 8 mm on lead shoots) and 1–1.5 mm (1⁄32–1⁄16 in) broad, and derive from an adnate petiole. The juvenile leaves (on young seedlings only) are needle-like, 5–10 mm (3⁄16–3⁄8 in) long. The cones are berry-like, globose to bilobed, 5–7 mm (3⁄16–9⁄32 in) 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 (3⁄32–5⁄32 in) long, and shed their pollen in early spring. It is dioecious, producing cones of only one sex on each 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.

The species is native to northern North America, throughout most of Canada from Yukon east to Newfoundland, and in the United States in Alaska, and continentally from Montana east to Maine, reaching its furthest south in Wyoming and northern Illinois. Amongst the sites it occupies are rocky areas of the east slopes of the Rocky Mountains.[4]

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.

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  Plant at Pancake Bay sand dunes, Ontario, Canada
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  Juniperus horizontalis 'Wiltonii' as a garden plant

• Adams, R. P. (2004). Junipers of the World: The genus Juniperus. Trafford Publishing ISBN 1-4120-4250-X

• USDA Plants Profile for Juniperus horizontalis (creeping juniper)
• Gymnosperm Database: Juniperus horizontalis Archived 2006-04-30 at the Wayback Machine
• Flora of North America: Juniperus horizontalis
• Plantmaps.com: Interactive Distribution Map of Juniperus horizontalis Archived 2017-03-19 at the Wayback Machine
• Lady Bird Johnson Wildflower Center, NPIN Database: Juniperus horizontalis (Creeping juniper, Creeping savin)

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