_Corylus_ (Hazel-nut, Fig. 329). The long, cylindrical ♂-catkins pass the winter naked, 2–3 together, on short branches. The very small ♀-catkins are enclosed in buds, in which they pass the winter; these buds are situated in the axils of the fallen foliage-leaves, and it is only by their larger size that they may be distinguished from the ordinary foliage-buds. In spring the ♀-catkins are easily recognised by their red, projecting stigmas (Fig. 329 _A_). The cupule--the “husk”--is tubular, fringed, and envelopes the nut. ~The leaves are alternate and unsymmetrical, the external side being larger than the internal; this is connected with the vernation, the blade being conduplicate in the bud; the stipules are deciduous. The bud-scales are formed of stipules, the most internal having a leaf-blade attached to them which is suppressed in the external ones. The cotyledons remain underground on germination.~ [Illustration: FIG. 329.--_Corylus avellana_: _A_ branch at the time of flowering with ♂-and ♀-catkins; _B_ ♂-flower with subtending-leaf (bract) and two bracteoles; _C_ the same without the anthers; _D_ view of interior of ♀-dichasium shortly after fertilisation; _E_ young fruit with cupule; _F_ similar one with the cupule opened; _G_ mature ♀-fruits; _H_ nut.] _Carpinus_ (_C. betulus_, Hornbeam). The ♂-and ♀-catkins do not appear till the leaves are shooting. The ♀-catkin in this instance is also long and cylindrical. The cupule in _C. betulus_ is 3-lobed, and to a slight extent only embraces the base of the ribbed nut (Fig. 331); each lobe corresponds to a floral-leaf. ~Whilst the carpels are placed medianly in _Corylus_, in _Carpinus_, on the other hand, they are situated transversely, as in the case of the _Betulaceæ_. The lamina of the leaf is not conduplicate in the bud, but flat, and folded only along the lateral veins, which are also indicated in the form of the fully-developed leaf; otherwise the vegetative characters are essentially the same as in the Hazel. The cotyledons are aerial.--_Ostrya_ resembles the Hornbeam, but the cupule completely envelopes the nut, as a sac open at the apex (Eur., N. Am., Japan).~ N. Am., Asia, and Europe; 25 species.--Fossil forms in the Oligocene. Wind-pollinated. USES. As timber (_Carpinus betulus_) and firewood. The fruits of _C. avellana_ (ordinary Hazel-nut), _C. tubulosa_ (Lambert’s nut) and _C. colurna_ (Turkish Filbert) are edible. [Illustration: FIG. 330.--Diagrams of the ♂-flower (_A_) of _Corylus_ and the dichasium of the ♀-flowers (_B_).] [Illustration: FIG. 331.--Nut of the Hornbeam with cupule.]