Juniperus horizontalis

Juniperus horizontalis
	Foliage and cones
Conservation status
	; Least Concern (IUCN 3.1)
	; Secure (NatureServe)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Gymnospermae
Division:	Pinophyta
Class:	Pinopsida
Order:	Cupressales
Family:	Cupressaceae
Genus:	Juniperus
Species:	J. horizontalis
Binomial name
	Juniperus horizontalis; Moench 1794
	Natural range of Juniperus horizontalis
Synonyms
	Juniperus prostrata Pers. 1807 ; Juniperus repens Nutt. 1818 ; Juniperus racemosa Risso 1826 ; Juniperus hudsonica Forbes 1839 ; Sabina prostrata (Pers.) Antoine 1857 ; Sabina racemosa (Risso) Antoine 1857 ; Sabina horizontalis (Moench) Rydb. 1912;

Juniperus horizontalis, the creeping juniper or creeping cedar,^[4] is a low-growing shrubby juniper native to northern North America, throughout most of Canada from Yukon east to Newfoundland, and in some of the northern United States.

Description

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.

Distribution and habitat

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.^[5]

Cultivation and uses

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.

Gallery

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

References

^ Farjon, A. (2013). "Juniperus horizontalis". IUCN Red List of Threatened Species. 2013: e.T42237A2965318. doi:10.2305/IUCN.UK.2013-1.RLTS.T42237A2965318.en. Retrieved 13 November 2021.
^ NatureServe (2024). "Juniperus horizontalis". Arlington, Virginia. Retrieved 18 August 2024.
^ Juniperus horizontalis The Plant List (2010). Version 1. Published on the Internet; http://www.theplantlist.org/ 22 Nov. 2011
^ Bailey, L.H.; Bailey, E.Z.; the staff of the Liberty Hyde Bailey Hortorium. 1976. Hortus third: A concise dictionary of plants cultivated in the United States and Canada. Macmillan, New York.
^ Arno, Stephen F.; Hammerly, Ramona P. (2020) [1977]. Northwest Trees: Identifying & Understanding the Region's Native Trees (field guide ed.). Seattle: Mountaineers Books. p. 174. ISBN 978-1-68051-329-5. OCLC 1141235469.

External links

[iucn_status_13_November_2021-1] Farjon, A. (2013). "Juniperus horizontalis". IUCN Red List of Threatened Species. 2013: e.T42237A2965318. doi:10.2305/IUCN.UK.2013-1.RLTS.T42237A2965318.en. Retrieved 13 November 2021.

[NatureServe-2] NatureServe (2024). "Juniperus horizontalis". Arlington, Virginia. Retrieved 18 August 2024.

[tpl-3] Juniperus horizontalis The Plant List (2010). Version 1. Published on the Internet; http://www.theplantlist.org/ 22 Nov. 2011

[Hortusthird-4] Bailey, L.H.; Bailey, E.Z.; the staff of the Liberty Hyde Bailey Hortorium. 1976. Hortus third: A concise dictionary of plants cultivated in the United States and Canada. Macmillan, New York.

[:02-5] Arno, Stephen F.; Hammerly, Ramona P. (2020) [1977]. Northwest Trees: Identifying & Understanding the Region's Native Trees (field guide ed.). Seattle: Mountaineers Books. p. 174. ISBN 978-1-68051-329-5. OCLC 1141235469.

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