1. =Córylus Americàna=, Walt. (WILD HAZELNUT.) Leaves roundish heart-shaped, pointed, doubly serrate; stipules broad at base, acute, and sometimes cut-toothed; twigs and shoots often hairy. Involucre of the fruit open to the globose nut, the two leaf-like bracts very much cut-toothed at the margin and thick and leathery at the base. Merely a shrub, 5 to 6 ft. high; quite common throughout. [Illustration: C. rostràta.] 2. =Córylus rostràta=, Ait. (BEAKED HAZELNUT.) Leaves but little or not at all heart-shaped; stipules linear-lanceolate. The involucre, extending beyond the nut in a bract like a bottle, is covered with stiff, short hairs. Shrub, 4 to 5 ft. high. Wild in the same region as Corylus Americana, but not so abundant. [Illustration: C. Avellàna.] 3. =Córylus Avellàna=, L. (EUROPEAN HAZEL. FILBERT.) Leaves roundish-cordate, pointed, doubly serrate, nearly sessile, with ovate-oblong, obtuse stipules; shoots bristly. Involucre of the fruit not much larger than the large nut (1 in.), and deeply cleft. A small tree or shrub, 6 to 12 ft. high, from Europe; several varieties in cultivation. GENUS =86. ÓSTRYA.= Slender trees with very hard wood, brownish, furrowed bark, and deciduous, alternate, simple, exstipulate, straight-veined leaves. Flowers inconspicuous, in catkins. Fruit hop-like in appearance, at the ends of side shoots of the season, hanging on through the autumn. [Illustration: O. Virgínica.] 1. =Óstrya Virgínica=, Willd. (IRON-WOOD. AMERICAN HOP-HORNBEAM.) Leaves oblong-ovate, taper-pointed, very sharply doubly serrate, downy beneath, with 11 to 15 straight veins on each side of the midrib; buds acute. The hop-like fruit 2 to 3 times as long as wide; full grown and pendulous, 1 to 3 in. long, in August, when it adds greatly to the beauty of the tree. A small, rather slender tree, 30 to 50 ft. high, with the bark on old trees somewhat furrowed; wood white and very hard and heavy; common in rich woods, and occasionally cultivated. [Illustration: O. vulgàris.] 2. =Óstrya vulgàris=, Willd. (EUROPEAN HOP-HORNBEAM.) This species from Europe is much like the American one, but has longer, more slender, more pendulous fruit-clusters. Occasionally cultivated. GENUS =87. CARPÌNUS.= Trees or tall shrubs with alternate, simple, straight-veined leaves, and smooth and close gray bark. Flowers in drooping catkins, the sterile flowers in dense cylindric ones, and the fertile flowers in a loose terminal one forming an elongated, leafy-bracted cluster with many, several-grooved, small nuts, hanging on the tree till late in the autumn. [Illustration: C. Caroliniàna.]