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deciduous trees, belonging to the order Betulacez, agreeing with the genus Carpinus in the characters of the branchlets, buds, foliage, and staminate flowers. Pistillate flowers, in dense erect spikes, inserted in pairs on the base of ovate acute leafy scales, each flower enclosed in a sac-like involucre, formed by the union of a bract and two bracteoles, which is open at the apex at the time of flowering, after- wards becoming closed. Calyx dentate, adnate to the two-celled inferior ovary ; style short, divided into two linear subulate stigmatic branches ; ovules solitary in each cell. Fruits: disposed in stalked ovoid strobiles, composed of densely imbri- cated involucres, which are vesicular, closed, flattened, membranous, longitudinally nerved, reticulate, pubescent at the apex, and hirsute at the base with sharp, rigid, stinging hairs. Nutlet, sessile in the involucre, ovoid, compressed, longitudinally ribbed, crowned by the remains of the calyx; seed solitary, pendulous.

Four species of Ostrya have been distinguished :—Ostrya Knowltonz, Coville, a rare tree in Arizona, not yet introduced, and three species, occurring in North America, Eastern Asia, and Europe and Asia Minor, which are so closely allied that they have been considered by most botanists to be only geographical races of one species. These three species are all in cultivation, and as they can be distinguished (see Key to Carpinus and Ostrya, p. 526), will be treated by us separately.

A tree attaining 60 feet in height and 10 feet in girth; stem cylindrical, bark greyish, finely fissured, and scaly. Young branchlets with dense appressed