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trees belonging to the order Betulaceæ. Leaves, alternate, distichous on the branchlets, stalked, ovate, doubly-serrate, penninerved, the nerves ending in the points of the teeth ; stipules scarious, caducous or persistent. Flowers appearing in early spring with the unfolding of the leaves, unisexual, moncecious, without petals. Staminate flowers in pendulous, cylindrical catkins, arising from buds produced near the ends of lateral branches of the previous year; stamens, three to twenty, crowded on a pilose receptacle adnate to the base of a concave scale; filaments short, two- branched, each branch bearing a one-celled anther, tipped with a cluster of long hairs. Pistillate flowers, in loose, semi-erect catkins, which are terminal on the branchlets of the year; in pairs at the base of an ovate, acute, deciduous scale ; each flower sub- tended by a small bract and two minute bracteoles, and consisting of a two-celled ovary, surmounted by a minute epigynous calyx and two elongated styles ; each cell containing one ovule.

Fruit, in pendent, stalked strobiles, composed of imbricated, foliaceous or mem- branous involucres, resulting from the developed bract and bracteoles of the flower, each with a nutlet at its base. Nutlet, ovoid, compressed, longitudinally ribbed, crowned by the calyx and remains of the style, one-seeded, and falling from the involucre in autumn. Seed, filling the cavity of the nutlet, without albumen ; cotyledons fleshy, carried above ground in germination.

The genus consists of about eighteen species inhabiting the temperate regions of North America, Europe, and Asia. Two sections are distinguished :—

I. Sargent, Silva N. Amer. ix. 40 (1896).


 * Scales of the staminate catkins lanceolate, stalked. Fruit-involucres, membranous, infolded below, completely covering the nutlet, closely imbricated in the strobile. Trees with scaly bark. Two species, C. japonica, Blume, and C. cordata, Blume.

II. Sargent, loc. cit.


 * Scales of the staminate catkins ovate, sub-sessile. Fruit-involucres, foliaceous, open or only slightly infolded over the nutlets, loosely imbricated in the strobile. Trees usually with smooth bark. This section includes the remaining species.