Northern Ontario Plant Database

Plant Description

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The Genus Cornus

Cornaceae (Dogwood Family)

There are 8 species of Cornus in Ontario. Most are shrubs characterized by simple, opposite, elliptic leaves with pinnate, arcuate veins – veins that curve inward towards the tip of the leaf. Exceptions to the shrubby habit with opposite leaf arrangement include Cornus canadensis (bunchberry) and C. alternifolia (alternate-leaf dogwood). C. canadensis is a low, perennial forb with erect, herbaceous shoots that arise from slender underground rhizomes; it bears 2-3 pairs of opposite leaves, which appear as a whorl of 4-6 leaves; sterile plants bear 2 pairs of leaves, while flowering plants have 3 pairs of leaves. Cornus alternifolia (alternate-leaf dogwood) is a tall shrub, like the other woody Cornus species, but it has alternate rather than opposite leaves.

The flowers of Cornus have a small, inconspicuous, 4-toothed calyx, 4 white lanceolate petals, and 4 stamens. The inferior ovary is topped by a nectar-producing disk, which may be white or pinkish, and persists as a dark dot, with the persistent style, at the tip of the fruit. The inferior ovary develops into a 1- or 2-seeded drupe, coloured white, red, blue, or purplish-black; the stalks of the inflorescence are often brightly coloured in fruit. Flowers are typically arranged in a few- to many-flowered terminal inflorescence (cyme or panicle), but two species, Cornus canadensis (bunchberry) and Cornus florida (flowering dogwood), have large, showy bracts subtending the flower clusters.

Of the 8 Ontario Cornus species, 5 occur in northern Ontario, but only 2 species, Cornus sericea (red osier dogwood, formerly known as C. stolonifera) and the herbaceous C. canadensis (bunchberry) occur throughout Ontario. Two species (C. drummondii, C. florida) are restricted to southernmost Ontario.

Go to Cornus key for northern Ontario species.

Go to Cornus comparison chart for northern Ontario species.

Go to Cornus distribution chart for northern Ontario species.


Key to the dogwood (Cornus) species of Ontario

1a.	Plants low, perennial herbs arising from woody rhizomes.
Cornus canadensis (bunchberry, crackerberry)
1b.	Plants woody shrubs.		go to 2
	2a.	Flowers sessile, subtended by large white showy bracts.
	Cornus florida (flowering dogwood)
	2b.	Flowers stalked, not subtended by showy bracts.	go to 3
3a.	Leaves alternate.
Cornus alternifolia (alternate-leaf dogwood)
3b.	Leaves opposite.		go to 4
	4a.	Pith of 2-year stems white; leaves ovate, broadly elliptic, to nearly orbicular.	go to 5
	4b.	Pith of 2-year stems brownish or at least darker than the wood; leaves lanceolate, elliptic, to oblanceolate.	go to 6
5a.	Twigs red; leaves elliptic with 5-7 pairs of veins; fruits white.
Cornus sericea (red osier dogwood)
5b.	Twigs red; leaves elliptic with 5-7 pairs of veins; fruits white.
Cornus rugosa (roundleaf dogwood)
	6a.	Leaves scabrous above; plants restricted to the Lake Erie region.
	Cornus drummondii (roughleaf dogwood)
	6b.	Leaves smooth above; plants wider-ranging, but absent from the Lake Superior region and farther north.
	go to 6
7a.	Flowers in elongate clusters (panicles), fruits white on bright red stalks.
Cornus racemosa (gray dogwood, panicled dogwood)
7b.	Flowers in flat-topped clusters (cymes), fruits blue on greenish stalks.
Cornus obliqua (narrowleaf dogwood, pale dogwood, silky dogwood)

Comparison Chart of Ontario Cornus Species

Cornus Species	Leaf Surface & Texture	Flowers	Mature Fruits
	Perennial herbs with underground rhizomes and shoots with 4-6 leaves.
C. canadensis (bunchberry)	elliptic to ovate, smooth, appearing whorled	subtended by 4 large white showy bracts	red fruits, no stalks (sessile)
	Woody shrubs with alternate leaves and stems with white pith
C. alternifolia (alternate-leaf dogwood)	elliptic to ovate, smooth above	lacks showy bracts	dark blue fruits, red stalks
	Woody shrubs with opposite leaves and stems with white pith.
C. rugosa (roundleaf dogwood)	broadly ovate to ± orbicular, rough above, hairy beneath	lacks showy bracts	light blue fruits, red stalks
C. sericea (red osier dogwood)	elliptic to ovate, smooth above, hairy beneath	lacks showy bracts	white fruits, dark purple stalks
C. florida (flowering dogwood)	elliptic to ovate, smooth above & beneath	subtended by 4 large white showy bracts	red fruits, no stalks (sessile)
	Woody shrubs with opposite leaves and stems with brownish pith.
C. obliqua (narrowleaf dogwood)	lanceolate to narrow-elliptic, smooth above, hairy beneath	lacks showy bracts	blue fruits, green stalks
C. racemosa (gray dogwood)	elliptic to lanceolate,smooth above, hairy beneath	lacks showy bracts	white fruits, red stalks
C. drummondii (roughleaf dogwood)	lanceolate to ovate, rough above, hairy beneath	lacks showy bracts	white fruits, purplish-red stalks

Distribution of Cornus species in Ontario

Cornus Species [arranged northernmost to southernmost]	Region of Ontario
	Western	Northern [north of Lake Superior]	North-Central [Algoma to Nipissing]	South-Central and Southwest	Ottawa and Southeast
C. canadensis	yes	yes	yes	yes	yes
C. sericea (= C. stolonifera)	yes	yes	yes	yes	yes
C. rugosa	yes	[N-shore Superior]	yes	yes	yes
C. alternifolia	yes	no	yes	yes	yes
C. racemosa	yes	no	no	yes	yes
C. obliqua	no	no	[Manitoulin]	yes	yes
C. florida	no	no	no	[southwest]	no
C. drummondii	no	no	no	[southwest]	no

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