The 6 genera and about 75 species belonging to this family are principally confined to the higher latitudes of the northern hemisphere. In North America there are 5 genera and about 30 species, of which the 5 genera and at least 9 species grow in West Virginia. The Common Hazelnut (Corylus americana, Walt.) and the Beaked Hazelnut (Corylus rostrata, Ait.) are both common shrubs of the State. The Smooth Alder (Alnus rugosa, (DuRoi) Spreng.) and the Hoary Alder (Alnus incana, (L.) Moench.) are both to be found, the former abundant along our streams, and the latter rare in upland swamps. Alnus alnobetula (Ehrh.) K K. is also reported from Greenbrier, Fayette, and Randolph counties.

This family produces products of great value. The wood of Birches is used extensively for furniture and interior finish, and for fuel. Black Birch supplies a volatile oil of considerable importance. The wood of some of the Alders is becoming valuable on account of its use in the manufacture of gunpowder, and the fruits of the Hazelnuts bring a good price on the market. The following are our tree genera:

Ostrya, (page 73).—Four species of Hop Hornbeam or Ironwood are known, 2 being found in North America. One of these is limited in its range to the Grand Canyon of the Colorado, in Arizona; the other is widely distributed and is common locally in West Virginia.

Carpinus, (page 75).—Eleven species of Hornbeams are native to Asia and Europe and only 1 species is found in North America. This is abundant in most parts of West Virginia.

Betula.—This genus comprises 25 known species of trees and 10 species of shrubs. About 15 of these are native to North America and 3 to West Virginia. Besides our native species the Gray Birch (Betula populifolia, Marsh.) and varieties of White Birch (Betula alba, L.) are often planted for ornamental purposes.

KEY TO THE SPECIES OF BETULA

• Bark of the trunk light-colored with thin layers curling or peeling off.
• Outer bark yellowish, fruits usually sessile; leaves usually rounded at base; twigs with slight wintergreen taste
• B. lutea, p. 79.
• Outer bark reddish-brown, inner bark tinged with red; fruits on slender stalks; leaves usually wedge-shaped at base; not aromatic
• B. nigra, p. 81.
• Bark of trunk rough, dark gray, without thin outer layers; bark of twigs with wintergreen taste
• B. lenta, p. 77.