The genus Cornus comprise a group of 30-50 species of mostly deciduous trees and shrubs in the family Cornaceae commonly known as dogwoods. Some are herbaceous perennials; a few of the woody species are evergreen.

"Dogwoods" are divided into one to nine genera or subgenera (depending on botanical interpretation), four subgenera of which are enumerated here.

The name "dog-tree" entered English vocabulary by 1548, and had been further transformed to "dogwood" by 1614. Once the name dogwood was affixed to the tree, it soon acquired a secondary name as the Hound's Tree, while the fruits came to be known as dogberries or houndberries (the latter a name also for the berries of Black nightshade and alluding to Hecate's hounds).

One theory advances the word dogwood comes from dagwood, from the use of the slender stems of very hard wood for making 'dags' (daggers, skewers, arrows). The wood was also highly prized for making loom shuttles, tool handles, and other small items that required a very hard and strong wood.

Larger items were also made of dogwood such as the screw in basket-style wine or fruit presses; also made were the first styles of tennis rackets made out of the wood cut in thin strips.

Another earlier name of the dogwood in English is the whipple-tree. Geoffrey Chaucer uses the word whippletree in The Canterbury Tales ("The Knight's Tale", verse 2065) to refer to the dogwood. A large item made of dogwood, the whippletree, still bears the name of the tree from which it is carved. A whippletree is an element of the traction of a horse-drawn cart, which links the drawpole of the cart to the harnesses of the horses in file.

In botany and in colloquial use, the term "dogwood winter" may be used to describe a cold snap in spring.

Most dogwood species have opposite leaves and a few have alternate. The fruit of all species is a drupe with one or two seeds. Flowers have four parts.

Many species in subgenus Swida are stoloniferous shrubs, growing along waterways. Several of these are used in naturalizing landscape plantings, especially the species with bright red or bright yellow stems. Most of the species in subgenus Benthamidia are small trees used as ornamental plants. As flowering trees, they are of rare elegance and beauty, comparable to Carolina silverbell, Canadian serviceberry, and the Eastern Redbud for their ornamental qualities.

The fruit of several species in the subgenera Cornus and Benthamidia is edible, though without much flavour. The berries of those in subgenus Swida are mildly toxic to people, though readily eaten by birds. Dogwoods are used as food plants by the larvae of some Lepidoptera species including Emperor Moth, The Engrailed, Small Angle Shades and the following case-bearers of the genus Coleophora: C. ahenella, C. salicivorella (recorded on Cornus canadensis), C. albiantennaella, C. cornella and C. cornivorella (The latter three feed exclusively on Cornus). They were used by pioneers to brush their teeth. The pioneers would peel off the bark, bite the twig and then scrub their teeth.