Northern Ontario Plant Database

Plant Description

Vaccinium ovalifolium Sm.

En: ovalleaf bilberry, blue bilberry, Alaska blueberry
Fr: airelle à feuilles ovées, airelle bleue, airelle à feuilles ovales

Ericaceae (Blueberry Family)

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General: A low deciduous shrub, 3—12 dm, of moist shaded habitats, with open spreading branches; uncommon in Ontario and restricted in range to the Algoma District.

Synonym: Vaccinium alaskaense Howell

Stems/twigs: Young branches are green, smooth (glabrous), and longitudinally angled. Winter twigs and buds are often reddish-brown on the upper surface, but green beneath. True terminal buds are absent; the false or pseudoterminal bud is subtended by a slender extension of the undeveloped stem tip. This spine-like structure is also visible at the base of the each year's growth. The ovoid buds have 2 smooth outer valvate bud scales (the scales meet at their edges); pseudoterminal buds are larger than the lower lateral buds; leaf scars are small and hemispherical with a single bundle trace scar. Older stems are purplish gray to dark brown with flakey bark.

Leaves: Alternate, simple, and pinnately-veined. The short petioles, 1—2 mm long, bend slightly so that leaves of each branch are displayed in a single flat plane. Young leaves are often elliptic, while fully expanded leaf blades are broadly oval, ovate, or nearly circular (orbicular) and 1.5—5 cm long by 0.5—1.8 cm wide. Leaf blades are green to bluish-green and dull above, glabrous on both surfaces, and paler beneath. Bases are tapering to rounded, apices are blunt (obtuse) to rounded or slightly indented (retuse), and margins are entire or with a few blunt teeth near the base. Ovalleaf bilberry leaves have a thinner, more membranaceous texture than the stiffer, somewhat coriaceous leaves of most blueberries.

Flowers: Single flowers are borne in leaf axils of the current year's growth. Flowers are short-stalked and pendant, pedicels are 1—5 mm long. The calyx has 5 very short broad lobes; the corolla is pinkish-white, small, to 6 mm long, urn-shaped (urceolate), narrowed and with 5 small reflexed lobes at the mouth of the corolla. The 10 stamens have awned anthers with elongate terminal pores through which pollen is shed; the single pistil has an inferior ovary and a single style, surrounded at the base by a nectar disk. Flowers bloom in early spring, before or just as the first leaves emerge.

Fruit: A globose dark blue-black berry, usually with a pale (glaucous) bloom easily removed when rubbed. Berries are 6—9 mm in diameter and have a circular scar at the top, marking where the calyx lobes had been attached. Although not as sweet or tasty as those of other blueberry species, the berries are edible. Fruits mature in late summer.

Habitat and Range: Very moist to well-drained rocky soils of shady mixedwood forests, at the base of rocky ledges and slopes, and often occupying a narrow zone of moist soil near the base of slopes adjacent to ponds and peatlands. Vaccinium ovalifolium is a Cordilleran disjunct, with its primary range occuring in the mountains of western North American (the Pacific Cordillera). Smaller separate (disjunct) populations occur in the Algoma District of Ontario, as well as in calcareous regions of Newfoundland and Labrador, Quebec, and the Maritimes; it is also native to eastern Asia. The ovalleaf bilberry can be found near coastal areas of the eastern Superior region, between SSM and Wawa, and on the Slate Islands; it is absent from all other regions of Ontario.

Similar Species: Bilberries can be distinguished from true blueberries by the number and arrangement of their flowers. Bilberries bear solitary flowers in the axils of their leaves, while blueberries bear terminal or lateral clusters (racemes) of several flowers. Bilberry flowers also have stamens with 2 downward-pointing awn on the back of the anthers, while blueberry flowers have awnless anthers, although both bilberries and blueberries shed their pollen through elongate terminal pores. Common blueberry species native to northern Ontario include lowbush blueberry (Vaccinium angustifolium Aiton), which has glabrous leaves and warty stems, and velvetleaf blueberry (Vaccinium myrtilloides Michx.), which has finely hairy leaves and downy stems; both blueberries have elliptic leaves with acute apices and tapering bases.