Setula.] LXXIII. AMENTACE^B. 405 



the nuts, which are small and seed-like, flat, surrounded by a scarious 

 wing. 



A small genus, confined to the northern hemisphere, and not reach- 

 ing the tropics. 



Tree, with broadly ovate, usually pointed leaves . . . . . 1. B. alba. 

 Shrub with small, orbicular leaves 2. B. nana. 



1. B. alba, Linn. (fig. 912). Common B.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, north Asia, and North 

 America, more limited to mountain districts in southern Europe. 

 Extends all over Britain. Fl. spring, before the leaves are fully out. [In 

 the ordinary B. alba the side lobes of the fruiting bracts are spread- 

 ing ; in var. glutinosa they are more erect ; in the latter the twigs are 

 '^ glabrous or pubescent, and the leaves more or less glutinous.] 

 ^ 2. B. nana, Linn. (fig. 913). Dwarf B. 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 mountains of central Europe. Not uncommon in the Highlands 

 of Scotland, but rare in the north of England, and unknown in Ireland. 

 Fl. spring. 



IV. CARPINUS. HOKNBEAM. 



Flowers monoecious, the males* in cylindrical catkins, with broad, 

 sessile scales. Stamens about 12 within each scale, without inner scales 

 or perianth ; the anther-cells distinct, on very short, forked filaments. 

 Female catkins slender, the scales lanceolate and deciduous. Flowers 

 2 within each scale, each 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. 0. Betulus, Linn. (fig. 914). Common ff.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 1J inches 

 long, less droopine than in the allied genera j the anthers crowned b^ 



