Cornus is a genus of about 30–60 species[Note 1] of woody plants in the family Cornaceae, commonly known as dogwoods, which can generally be distinguished by their blossoms, berries, and distinctive bark.[3] Most are deciduous trees or shrubs, but a few species are nearly herbaceous perennial subshrubs, and a few of the woody species are evergreen. Several species have small heads of inconspicuous flowers surrounded by an involucre of large, typically white petal-like bracts, while others have more open clusters of petal-bearing flowers. The various species of dogwood are native throughout much of temperate and boreal Eurasia and North America, with China, Japan, and the southeastern United States being particularly rich in native species.
Species include the common dogwood Cornus sanguinea of Eurasia, the widely cultivated flowering dogwood (Cornus florida) of eastern North America, the Pacific dogwood Cornus nuttallii of western North America, the Kousa dogwood Cornus kousa of eastern Asia, and two low-growing boreal species, the Canadian and Eurasian dwarf cornels (or bunchberries), Cornus canadensis and Cornus suecica respectively.
Depending on botanical interpretation, the dogwoods are variously divided into one to nine genera or subgenera; a broadly inclusive genus Cornus is accepted here.
The name "dog-tree" entered the English vocabulary before 1548, becoming "dogwood" by 1614. Once the name dogwood was affixed to this kind of 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, alluding to Hecate's hounds). Another theory advances the view that "dogwood" was derived from the Old English dagwood[citation needed] (dagwood is a form which is unattested), from the use of the slender stems of its very hard wood for making sharp objects:[4] "dags"(daggers, skewers, and arrows).[5][6] Another, earlier name of the dogwood in English, is the "whipple-tree". Geoffrey Chaucer uses "whippletree" in The Canterbury Tales ("The Knight's Tale", verse 2065) to refer to the dogwood. A whippletree is also an element of the traction of a horse-drawn cart, linking the drawpole of the cart to the harnesses of the horses in file; these items still bear the name of the tree from which they are commonly carved.
Dogwoods have simple, untoothed leaves with the veins curving distinctively as they approach the leaf margins. Most dogwood species have opposite leaves, while a few, such as Cornus alternifolia and C. controversa, have their leaves alternate. Dogwood flowers have four parts. In many species, the flowers are borne separately in open (but often dense) clusters, while in various other species (such as the flowering dogwood), the flowers themselves are tightly clustered, lacking showy petals, but surrounded by four to six large, typically white petal-like bracts.
The fruits of all dogwood species are drupes with one or two seeds, often brightly colorful. The drupes of species in the subgenus Cornus are edible. Many are without much flavor. Cornus kousa and Cornus mas are sold commercially as edible fruit trees. The fruits of Cornus kousa have a sweet, tropical pudding like flavor in addition to hard pits. The fruits of Cornus mas are both tart and sweet when completely ripe. They have been eaten in Eastern Europe for centuries, both as food and medicine to fight colds and flus. They are very high in vitamin C. However, those of species in subgenus Swida are mildly toxic to people, though readily eaten by birds.
