Cornus amomum ssp. obliqua (Raf.) J.S. Wilson

Swamp Dogwood

Cornus amomum  plant

Family - Cornaceae

Habit - Shrubs, 1-4 m tall, usually solitary.

Stems - Twigs reddish brown to purplish brown, densely tomentose-hairy when young, becoming glabrous or nearly so with age, the pith brown. Bark smooth or with shallow fissures, not becoming corky, reddish brown, usually with small, slightly raised to somewhat warty, lighter dots.

Cornus amomum  twigNew season's growth.

Cornus amomum  stemOlder stem growth.

Leaves - Opposite, simple, petiolate, usually evenly dispersed along the branches, the petiole 0.5-1.5 cm long, tomentose. Leaf blades 4-9 cm long, 1-4 cm wide, narrowly lanceolate or narrowly elliptic to ovate, angled or tapered at the base, angled or more commonly tapered to a bluntly or sharply pointed tip, the surfaces sparsely to moderately pubescent with appressed, straight, T-shaped hairs and somewhat spreading, V-shaped or Y-shaped hairs, the upper surface dark green, the lower surface whitened, the lateral veins 4-6 pairs, these relatively evenly spaced, abaxially expressed.

Cornus amomum leaf1Leaf adaxial.

Cornus amomum  leafLeaf abaxial.

Cornus amomum  leavesPressed leaves.

Inflorescence - Flat-topped panicles (cymes) at branch tips, broader than tall. Bracts absent or rarely a few at the branch points and these minute and scalelike. Flower stalks 2-3 mm long, hairy, becoming reddish brown as the fruits mature.

Cornus amomum inflorescenceInflorescence.

Cornus amomum inflorescence2

Flowers - Sepals 4, 0.6-1.2 mm long. Petals 4, 3.5-5.0 mm long, narrowly oblong-lanceolate, white to cream-colored. Style 2-4 mm long, relatively stout, broadened toward the tip. Stamens 4. Five parted flowers occasionally seen.

Cornus amomum flowers2Flowers.

Cornus amomum flowers5-merous flowers.

Fruits - Globose drupe 5-8 mm in diameter, dark blue, sometimes with white blotches. Stone with 6-9 sharply angled longitudinal ridges.

Cornus amomum  fruits

Flowering - May - July.

Habitat - Streambanks, pond margins, fens, bottomland forests, wet prairies, pastures, roadsides.

Origin - Native to U.S.

Lookalikes - Cornus drummondii, Cornus foemina.

Other info. - This species is found scattered throughout Missouri, almost always in wet places. Outside of Missouri its range extends into the upper Midwest, New England, and Canada. Though similar in appearance to other dogwood species, it can be distinguished by its narrow leaves and flat-topped inflorescences which are broader than tall. The young twigs are also densely hairy. The image above doesn't do the fruits justice; they are brilliant blue.

Circumscriptions within the Cornus genus have been somewhat controversial. Yatskievych and others have assigned Missouri plants to C. amomum ssp. obliqua. Other authors have elevated the plant to its own species, Cornus obliqua. Whatever its name, this species has the narrowest leaves of any Cornus in the state. Hybrids can occur when other species of dogwood are growing in close proximity, and the resulting plants can be taxonomically confusing.

Photographs taken near Hercules Glade, Mark Twain National Forest, Taney County, MO., 9-10-99, and in Ripley County, MO., 6-5-04 (DETenaglia); also in Kaintuck Hollow Natural Area, Phelps County, MO, 6-9-2018 (SRTurner).


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