6. =Betula ngra=, L. (RIVER OR RED BIRCH.) Leaves 2 to 3 in. long, rhombic-ovate, acute at both ends, distinctly doubly serrate, bright green above; glaucous beneath when young; on petioles only 1/6 their length. Twigs brown to cinnamon-color, and downy when young. A medium-sized tree, 30 to 50 ft. high, usually growing on the edges of streams, the old trunks having a very s.h.a.ggy, loose, torn, reddish-brown bark. Wild in Ma.s.sachusetts, south and west; often cultivated.

GENUS =84. aLNUS.=

Shrubs or small trees with deciduous, alternate, simple, straight-veined leaves with large stipules that remain most of the season. Flowers in catkins. Fruit a small, scaly, open, woody cone, remaining on the plant throughout the year.

* Native species; growing in wet places. (=A.=)

=A.= Leaves rounded at base; whitened beneath; found north of 41 N. Lat 1.

=A.= Leaves acute or tapering at base; southward. (=B.=)

=B.= Flowering in the spring 2.

=B.= Flowering in the autumn 3.

* Cultivated species; from Europe; will grow in dry places 4, 5.

[Ill.u.s.tration: A. incana.]

1. =alnus incana=, Willd. (SPECKLED OR h.o.a.rY ALDER.) Leaves 3 to 5 in.

long, broadly oval or ovate, rounded at base, sharply serrate, often coa.r.s.ely toothed, whitened and mostly downy beneath; stipules lanceolate and soon falling. Fruit orbicular or nearly so. A shrub or small tree, 8 to 20 ft. high, with the bark of the trunk a polished reddish green; common along water-courses north of 41 N. Lat.; sometimes cultivated.

[Ill.u.s.tration: A. serrulata.]

2. =alnus serrulata=, Willd. (SMOOTH ALDER.) Leaves 2 to 4 in. long, thickish, obovate, acute at base, sharply and finely serrate, green both sides, smooth or often downy beneath; stipules yellowish green, oval, and falling after 2 or 3 leaves have expanded above them. Fruit ovate.

Rather a shrub than a tree, 6 to 12 ft. high, common along streams south of 41 N. Lat. In the Southern States it sometimes forms a tree 30 ft.

high.

[Ill.u.s.tration: A. maritima.]

3. =alnus maritima=, Muhl. (SEASIDE ALDER.) Smooth; leaves oblong-ovate to obovate, with a tapering base, sharply serrulate; petiole slender; color bright green, somewhat rusty beneath. Flowering in the autumn.

Fruiting catkin large, to 1 in. long, in. thick, usually solitary, ovoid to oblong. A small tree, 15 to 25 ft. high. Southern Delaware and eastern Maryland, near the coast.

[Ill.u.s.tration: A. glutinsa.]

4. =alnus glutinsa=, L. (EUROPEAN ALDER.) Leaves roundish, wedge-shaped, wavy-serrated, usually abrupt at tip, glutinous; sharply and deeply incised in some varieties. Fruit oval, in. long. A medium-sized tree, 25 to 60 ft. high, of rapid growth, often cultivated under several names; the most important being vars. _laciniata_ (cut-leaved), _quercifolia_ (oak-leaved), and _rubrinervis_ (red-leaved).

[Ill.u.s.tration: A. cordiflia.]

5. =alnus cordiflia=, Ten. (HEART-LEAVED ALDER.) Leaves heart-shaped, dark green and shining. Flowers greenish-brown, blooming in March and April, before the leaves expand. A large and very handsome Alder, 15 to 20 ft. high, growing in much dryer soil than the American species.

Cultivated from southern Europe. Hardy after it gets a good start, but often winter-killed when young.

GENUS =85. CoRYLUS.=

Low trees and large shrubs with simple, alternate, deciduous, doubly serrate, straight-veined leaves. Flowers insignificant, in catkins in early spring. Fruit an ovoid-oblong bony nut, inclosed in a thickish involucre of two leaves with a lacerated frilled border; ripe in autumn.

* Leafy bracts of fruit forming a bottle-shaped involucre 2.

* Leafy bracts not bottle-shaped. (=A.=)

=A.= Involucre much longer than the nut 1.

=A.= Involucre but little longer than the nut 3.

[Ill.u.s.tration: C. Americana.]

1. =Corylus Americana=, 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.

[Ill.u.s.tration: C. rostrata.]

2. =Corylus rostrata=, 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.

[Ill.u.s.tration: C. Avellana.]

3. =Corylus Avellana=, 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. oSTRYA.=

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.

[Ill.u.s.tration: O. Virginica.]

1. =ostrya Virginica=, 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.

[Ill.u.s.tration: O. vulgaris.]

2. =ostrya vulgaris=, Willd. (EUROPEAN HOP-HORNBEAM.) This species from Europe is much like the American one, but has longer, more slender, more pendulous fruit-cl.u.s.ters. Occasionally cultivated.

GENUS =87. CARPNUS.=

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 cl.u.s.ter with many, several-grooved, small nuts, hanging on the tree till late in the autumn.

[Ill.u.s.tration: C. Caroliniana.]

1. =Carpnus Caroliniana=, Walt. (AMERICAN HORNBEAM. BLUE OR WATER BEECH.) Leaves ovate-oblong, pointed, sharply doubly serrate, soon nearly smooth. Fruit with the scales obliquely halberd-shaped and cut-toothed, in. long, nuts 1/8 in. long. A tree or tall shrub, 10 to 25 ft. high, with a peculiarly ridged trunk; the close, smooth gray bark and the leaves are much like those of the Beech. The wood is very hard and whitish. Common along streams; sometimes cultivated.

[Ill.u.s.tration: C. Betulus.]

2. =Carpnus Betulus=, L. (EUROPEAN HORNBEAM.) This cultivated species is quite similar to the American, but can be distinguished by the scales of the fruit, which are wholly halberd-shaped, having the basal lobes nearly equal in size, as shown in the cut; while the American species has scales only half halberd-shaped.

GENUS =88. QUeRCUS.=