SMOOTH ALDER.) Leaves 2 to 4 1/2 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 deg. N. Lat. In the Southern States it sometimes forms a tree 30 ft.
high.

[Illustration: 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, 3/4 to 1 in. long, 1/2 in. thick, usually solitary,
ovoid to oblong. A small tree, 15 to 25 ft. high. Southern Delaware and
eastern Maryland, near the coast.

[Illustration: A. glutinosa.]

4. =Alnus glutinosa=, L. (EUROPEAN ALDER.) Leaves roundish,
wedge-shaped, wavy-serrated, usually abrupt at tip, glutinous; sharply
and deeply incised in some varieties. Fruit oval, 1/2 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).

[Illustration: A. cordifolia.]

5. =Alnus cordifolia=, 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.

[Illustration: C. Americana.]

1. =Corylus Americana=, Walt. (WILD HAZELNUT.) Leaves roundish
heart-shaped, pointed, doubly serrate; stipules broad at base, acute,
and sometimes cut-t