Through its cultivated varieties _Prunus avium_ is everywhere known in temperate climates as the Sweet Cherry. In the wild state it is variously called Mazzard, Bird, Wild, Crab and the Gean cherry. It is not as hardy a species as _Prunus cerasus_ and is, therefore, less generally grown but still is a favorite orchard, dooryard and roadside plant in all mid-temperate regions. It refuses to grow, however, in the warmest and coldest parts of the temperate zones. Wherever the species thrives as an orchard plant it is to be found growing spontaneously along fences and roadsides and in open woods from seeds distributed by birds. The fruits of these wild Sweet Cherries are usually small and the flesh thin and dry, often unpalatable; but, on the other hand, trees are sometimes found as escapes from cultivation which rival in their products the orchard-grown cherries. It is from reverted seedlings that the description of the species herewith given has been made. The number of cultivated varieties of _Prunus avium_ listed in _The Cherries of New York_ is 549. The habitat of the species and its history as a cultivated plant are given in the following chapter. A further point of horticultural interest as regards its habitat is that wherever found truly wild, as in its original home in southern and central Europe and Asia Minor, it is to be found in moderately dry, calcareous soils and seldom in the shade, preferring always warm, sunny sites, as gravelly or stony hillsides. These predilections cling to the species in its cultivated varieties. _Prunus avium_ differs from _Prunus cerasus_ in an important horticultural character as the two species grow spontaneously--the former suckers from the root little or not at all, making it a suitable plant for a stock in orchard work, while the latter suckers so much as to make it unfit for use as a stock. _Prunus avium_ is variously divided by botanists and pomologists. Whatever distinct forms of the species may exist in the wild state, they are now interminably confused by hybridization under cultivation. It is impossible to divide the species into botanical varieties from the characters of the horticultural varieties, as many botanists have attempted to do. The species can be roughly divided into two pomological groups, the distinguishing character being the texture of the flesh. Sweet Cherries with soft, tender flesh form one group known by pomologists under the French group name Guigne or the English Gean. These are also the Heart cherries of common parlance. These soft-fruited cherries may again be divided into dark colored varieties with reddish juice and light colored sorts with colorless juice. Typical light colored Geans are Coe, Ida, Elton and Waterloo; dark colored ones are Black Tartarian, Early Purple and Eagle. It is to this group of cherries that Linnaeus gave the varietal name _Juliana_ and De Candolle the specific name _Cerasus Juliana_.