Shrubs, trees, or herblike shrubs, precocious, coetaneous, or serotinous. Young shoots pubescent, rarely glabrous; trichomes curly or straight, raised or appressed. Stem sympodial, rarely monopodial. Winter buds terminal or axillary, mixed or separate, covered or exposed. Petiole slightly furrowed adaxially; leaf blade narrowly elliptic, elliptic, oblong, or ovate, glabrous to densely pubescent, lateral veins actinodromous, often raised abaxially. Inflorescence formed in previous or current year; bracts covering inflorescence or not. Sepals 4, fused; teeth absent, minute, or variously triangular. Petals 4, free, spreading, oblong to orbicular, valvate. Filaments filiform or awn-shaped, longer than style, longer or shorter than petals; anthers whitish or yellow, rarely blue, red, or purplish, ellipsoid to narrowly ellipsoid or oblong, 2-loculed. Ovary obovoid, crowned by a disk. Fruit globose, ovoid, oblong, or ellipsoid, crowned by persistent calyx, disk, and style; stones globose, ovoid, ellipsoid, oblong, sometimes asymmetric, surface smooth or ribbed, apex rarely pitted.

The classification of Cornus has long been debated. The ranks and circumscriptions of subgroups vary considerably among taxonomists. The current treatment retains Cornus in the broad sense as defined by Linnaeus and represents a synthesis of Ferguson (J. Arnold Arbor. 47: 100–105. 1966), Murrell (Syst. Bot. 18: 469–495. 1993), and Xiang (Acta Phytotax. Sin. 25: 125–131. 1987). This treatment agrees with recent molecular phylogenetic analyses of Cornus. The genus can be conveniently divided into distinct groups, all of which at one time or another have been recognized at full generic level. The keys below take advantage of those groupings.

Cornus esquirolii H. Léveillé (Repert. Spec. Nov. Regni Veg. 13: 257. 1914) was identified as Adina racemosa (Siebold & Zuccarini) Miquel (Rubiaceae) by Lauener (Notes Roy. Bot. Gard. Edinburgh 32: 97. 1972).

Geographical distribution is the same as that of the family.