Swamp, or silky dogwood is an open, irregularly branched shrub that usually occurs as a solitary individual, usually in wet locations. Rarely, it takes the appearance of a small tree.
The leaves are opposite (alternate in one of our species), simple, entire, egg- to lance-shaped (longer than broad). Uppersides smooth, dark green; undersides paler and may be smooth or covered with minute, appressed white hairs. The 5 or 6 pairs of secondary leaf veins are strongly arched toward the leaf tip, becoming irregularly fused toward the leaf margin. The leaf stalk is hairy.
The flowers are in clusters at the tips of branches, with 4 white petals that are not very showy; appear May–July; in flat or sometimes indented to round-topped clusters, on very hairy, yellowish-brown stalks.
The fruits are berrylike (technically, drupes), spherical, blue (sometimes with white blotches), each fruit with 1 or 2 oblong seeds. The style from the flower persists as a tiny stalk at the tip of each fruit. Fruit stalks become reddish brown as fruits mature.
The twigs are slender, reddish brown to purplish brown, and densely hairy when young. Older twigs lack hairs.
Trunk bark is usually tight, red, with small, tan, slightly raised dots; some stems have shallow longitudinal splits in the outer bark.
Similar species: Missouri has 4 other species of dogwoods:
- Gray dogwood (stiff dogwood) (C. foemina) usually grows in swamps and other wet locations. It is scattered nearly statewide but absent from most of the Unglaciated Plains of northern Missouri. Identify it by its opposite leaves with mostly 3 or 4 pairs of side veins (not 5 or 6), light blue or mottled blue-and-white fruits, and young twigs smooth (not hairy).
- Rough-leaved dogwood (C. drummondii) commonly occurs in disturbed habitats and tolerates drier conditions than other dogwoods. It occurs statewide. It can hybridize with other dogwoods, and you may find an individual plant or a small colony (spread via root sprouts) with characteristics intermediate between the two parent species. These hybrids, if you find any, will be very hard to identify. Note the roughened upper leaf surface, the secondary veins somewhat crowded toward the leaf base (most secondary veins arise in the basal half of the leaf), and the white fruits.
- Alternate-leaved dogwood (C. alternifolia) is the only Missouri dogwood with alternate (not opposite) leaves. Fruits are dark blue or bluish black.
- Flowering dogwood (C. florida) prefers well-drained, acid-based soils and most common in the Ozarks. It is identified by its combination of opposite leaves, dense flowerheads with 4 showy bracts beneath the yellowish clusters of inconspicuous flowers, and oval red fruits. It is Missouri’s official state tree, producing lovely boughs of white inflorescences (flower clusters) in our springtime forests.