Cornus with nearly fifty species is widely distributed through the three continents of the northern hemisphere, and south of the equator is represented in Peru by a single species. Of the sixteen or seventeen species of the United States four are arborescent. Cornus is rich in tannic acid, and the bark and occasionally the leaves and unripe fruit are used as tonics, astringents, and febrifuges. Of exotic species, Cornus mas, L., is often planted in the eastern states as an ornamental tree, and its edible fruit is used in Europe in preserves and cordials. The wood of Cornus is hard, close-grained, and durable, and is used in turnery and for charcoal.
The generic name, from cornu, relates to the hardness of the wood produced by plants of this genus.
CONSPECTUS OF THE ARBORESCENT SPECIES OF THE UNITED STATES.
Flowers greenish, in a dense cymose head surrounded by a conspicuous corolla-like involucre of 4—6 white or rarely red scales, from terminal buds formed the previous summer; fruit ovoid, bright red, rarely yellow. Heads of flower-buds inclosed by the involucre during the winter; involucral scales 4, obcordate or notched at apex; leaves ovate to elliptic.1. [C. florida] (A, C). Heads of flower-buds inclosed only at base by the involucre during the winter; involucral scales 4—6, oblong to obovate, usually acute at apex; leaves ovate or rarely obovate.2. [C. Nuttallii] (B, G). Flowers cream color, in a flat cymose head, without involucral scales, terminal on shoots of the year; fruit subglobose, white or dark blue. Leaves opposite, scabrous above; fruit white.3. [C. asperifolia] (A, C). Leaves mostly alternate and clustered at the end of the branches, smooth above; fruit dark blue or rarely yellow.4. [C. alternifolia] (A, C).
1. [Cornus florida] L. Flowering Dogwood.
Leaves ovate to elliptic or rarely slightly obovate, acute and often contracted into a slender point at apex, gradually narrowed at base, remotely and obscurely crenulate-toothed on the somewhat thickened margins, and mostly clustered at the end of the branches, when they unfold pale and pubescent below and puberulous above, and at maturity thick and firm, bright green and covered with minute appressed hairs on the upper surface, pale or sometimes almost white and more or less pubescent on the lower surface, 3′—6′ long and 1½′—2′ wide, with a prominent light-colored midrib deeply impressed above, and 5 or 6 pairs of primary veins connected by obscure reticulate veinlets; in the autumn turning bright scarlet on the upper surface, remaining pale on the lower surface; petioles grooved, ½′—¾′ in length. Flowers: head of flower-buds appearing during the summer between the upper pair of lateral leaf-buds, inclosed by 4 involucral scales remaining light brown and more or less covered with pale hairs during the winter, and borne on a stout club-shaped puberulous peduncle ¼′ long or less during the winter and becoming 1′—1½′ in length; involucral scales beginning to unfold, enlarge and grow white in early spring and when the flowers open in March at the south to May at the north, when the leaves are nearly fully grown, forming a flat corolla-like cup 3′—4′ in diameter, becoming at maturity obovoid, 1′—1½′ wide, gradually narrowed below the middle and notched at the rounded apex, reticulate-veined, pure white, pink, or rarely bright red, deciduous after the fading of the flowers; flowers in dense many-flowered cymose heads, in the axils of broad-ovate nearly triangular minutely apiculate glabrous light green deciduous bracts, ⅛′ in diameter; calyx terete, slightly urceolate, puberulous, obtusely 4-lobed, light green; corolla-lobes strap-shaped, rounded or acute at apex, slightly thickened on the margins, puberulous on the outer surface, reflexed after anthesis, green tipped with yellow; disk large and orange-colored; style crowned with a truncate stigma. Fruit ripening in October, ovoid, crowned with the remnants of the narrow persistent calyx and with the style, bright scarlet or rarely yellow (f. xanthocarpa Rehd.), lustrous, ½′ long and ¼′ broad, with thin mealy flesh, and a smooth thick-walled slightly grooved stone acute at the ends, and 1 or 2-seeded; seeds oblong, pale brown.
A bushy tree, rarely 40° high, with a short trunk 12′-18′ in diameter, slender spreading or upright branches, and divergent branchlets turning upward near the end, pale green or green tinged with red when they first appear, glabrous or slightly puberulous, bright red or yellow-green during their first winter and nearly surrounded by the narrow ring-like leaf-scars, later becoming light brown or gray tinged with red; frequently toward the northern limits of its range a much-branched shrub. Winter-buds formed in midsummer; the terminal covered by 2 opposite acute pointed scales rounded on the back and joined below for half their length, and accompanied by 2 pairs of lateral buds, each covered by a single scale, those of the lower pair shedding their scales in the autumn and remaining undeveloped. Bark of the trunk ⅛′—¼′ thick, with a dark red-brown surface divided into quadrangular or many-sided plate-like scales. Wood heavy, hard, strong, close-grained, brown sometimes changing to shades of green and red, with lighter colored sapwood of 30—40 layers of annual growth; largely used in turnery, for the bearings of machinery, the hubs of small wheels, barrel-hoops, the handles of tools, and occasionally for engravers’ blocks.
Distribution. Usually under the shade of taller trees in rich well-drained soil; southern Maine to southern Ontario, southern Michigan, southeastern Kansas and eastern Oklahoma, and southward to central Florida and the valley of the Brazos River, Texas; on the mountains of northern Mexico; comparatively rare at the north; one of the commonest and most generally distributed inhabitants of the deciduous-leaved forests of the middle and southern states, ranging from the coast nearly to the summits of the high Alleghany Mountains. Trees with rose-colored or with pink involucral scales occasionally occur (var. rubra André). A variety with pendulous branches is known in gardens (var. pendula Dipp.); the var. xanthocarpa near Oyster Bay, Nassau County, Long Island, New York, and at Saluda, Polk County, North Carolina.
Often planted as an ornament of parks and gardens in the eastern states.