Betula. | LXXIII, AMENTACE. 405 
pendulous ovule in each. In the fruiting catkin the scales (formed of the 
catkin-scale, with the 2 inner ones combined) are somewhat enlarged and 
3-lobed, falling off with the nuts, which are small and seed-like, flat, sur- 
rounded by a scarious wing. 
A small genus, confined to the northern hemisphere, and not reaching 
the tropics, 
Tree, with broadly ovate, usually pointed leaves . < 2 6 . 1. B. alba. 
Shrub, with small, orbicular leaves . : A A A A . 2 B. nande 
1, B. alba, Linn. (fig. 910). Common Birch.—An elegant tree, with 
slender, often gracefully drooping branches, the white bark of the trunk 
readily peeling off in layers. Leaves usually broadly ovate, taper-pointed, 
and toothed, but varying from rhomboidal to triangular or broadly cordate, 
often trembling on their slender stalks like those of the Aspen, glabrous 
and shining, with minute glandular dots when young. Male catkins 
drooping, 1 to 2 inches long; the females shortly stalked, about 6 inches 
long when in flower, Fruiting catkins 1 to 1} inches, the scales wedge- 
shaped, fully 2 lines long, broadly 3-lobed. 
In woods, in northern and central Europe, Asia, and North America, 
more limited to mountain districts in southern Europe. Extends all over 
Britain. Fl. spring, before the leaves are fully out. [| B.glutinosa, Fries, 
is a variety with erect side-lobes of the fruiting bracts. | 
2. B.nana, Linn, (fig. 911). Dwarf Birch.—Usually a small shrub, 
but sometimes attains 20 feet. Leaves very shortly stalked, nearly orbi- 
cular, seldom above half an inch long, and not pointed. Catkins small 
and sessile, the males oblong or shortly cylindrical, the females scarcely 
above 3 lines long. Fruiting catkins about 6 lines long, the scales not so 
thin, nor so deciduous as in B. alba. 
In moors and bogs, in northern Europe, Asia, and America, and in the 
great mountain-chains of central Kurope and Asia. Not uncommon in the 
Highlands of Scotland, but rare in the north of England, and unknown in 
Ireland, #1. spring. 
IV. CARPINUS. HORNBEAM. 
Flowers moneecious, the males in cylindrical catkins, with broad, sessile 
scales. Stamens about 12 within each scale, without inner scales or pe- 
rianth ; the anther-cells distinct, on very short, forked filaments. Female 
catkins slender and loose, the scales lanceolate and deciduous. Flowers 2 
within each scale, each one enclosed in a hairy, unequally 3-lobed inner 
scale. Perianth combined with the ovary at the base, with a minute 
toothed border. Ovary 2-celled, with a pendulous ovule in each cell. 
Styles 2. Fruiting catkin much elongated, the inner scales enlarged into 
long, leafy, unequally 3-lobed bracts, each enclosing at its base a small 
nut. 
There are but very few European, Asiatic, or North American species, 
differing slightly from each other in the shape of the fruiting bracts. 
1, ©. Betulus, Linn. (fig. 912). Common Hornbeam.—A small tree, 
with numerous short, slender branches. Leaves stalked, ovate, pointed, 
doubly toothed, with parallel veins diverging from the midrib, usually 
downy in their axils underneath. Male catkins sessile, about 1} inches 
