Northern Ontario Plant Database

Plant Description

Juniperus communis L.

En: common juniper
Fr: genévrier commun
Oj: ogaawa/inzh, giizhigaandagizi

Cupressaceae (Juniper or cypress Family)

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General: A low evergreen shrub, to 1.5 m tall, with numerous stiff spreading branches. The resinous and aromatic cones of juniper are often referred to as juniper berries; they are used to flavour gin and as a seasoning with venison, turkey, and sauerbraten.

Taxonomy: Juniperus communis L. var. depressa Pursh is the variety found in Ontario. The typical variety, var. communis (common juniper), is native to Eurasia.

Stems/twigs: Young stems are green and smooth (glabrous); older stems are reddish-brown with somewhat shreddy bark.

Needles: Evergreen, simple, and sessile; in whorls of 3 needles at each node. Needles are stiff, green, narrowly linear-lanceolate, 8—15 mm long to 1.6 mm wide at the base, and taper gradually to a sharply pointed spiny (subulate) tip. The upper needle surface is curved upward (concave) and marked by a whitish (glaucous) central stripe, bordered on either side by a green margin of equal width.

Reproductive structures/cones: Unisexual, with separate male and female reproductive structures (cones) borne on different plants (dioecious). Cones are axillary and attached directly to the stem (sessile). Male (staminate) cones are small and produce pollen in late spring (May to early June); after pollen is shed, male cones drop from the branches. Female cones consist of 3—6 leathery scales that bear 1—3 ovules; seeds take 2 years to mature and are retained within the indehiscent cones. One-year-old cones are ovoid to globose, greenish to light blue with a thick glaucous coating; 2-year-old cones are globose and dark bluish-black, with or without a glaucous coating. Mature cones are berry-like, 6—9 mm in diameter, and contain 3 seeds.

Habitat and Range: Dry to somewhat moist, sandy or rocky soils, in open woods, alvars, fields, and on rock outcrops along roadsides. Ground juniper is native to boreal North America and has a trans-Canadian distribution. Ground juniper occurs throughout Ontario.

Similar Species: Canada yew (Taxus canadensis Marshall) is also a low evergreen shrub with pointed needles, but its needles are soft and flexible, flat rather than concave, green on both surfaces, and spirally arranged around the stem, with petioles bent to make the needles appear 2-ranked. Its single seed is surrounded by a fleshy red berry-like aril, open at the tip. Canada yew prefers moist shaded forest habitats.

Spruce (Picea) trees also have sharply pointed needles, but spruce needles are rounded to 4-angled in cross-section and spirally arranged around the stem.