rrate; both sides smooth and shining,
when young glutinous with resinous glands; leafstalks half as long as
the blades and slender, so as to make the leaves tremulous, like those
of the Aspen. Fruit brown, cylindrical, more or less pendulous on
slender peduncles. A small (15 to 30 ft. high), slender tree with an
ascending rather than an erect trunk. Bark chalky or grayish white, with
triangular dusky spaces below the branches; recent shoots brown, closely
covered with round dots.

[Illustration: B. papyrifera.]

2. =Betula papyrifera=, Marsh. (PAPER OR CANOE BIRCH.) Leaves 2 to 4 in.
long, ovate, taper-pointed, heart-shaped, abrupt or sometimes
wedge-shaped at the base, sharply and doubly serrate, smooth and green
above, roughly reticulated, glandular-dotted and slightly hairy beneath;
footstalk not over 1/3 the length of the blade. Fruit long-stalked and
drooping. A large tree, 60 to 75 ft. high, with white bark splitting
freely into very thin, tough layers. A variety, 5 to 10 ft. high (var.
_minor_), occurs only in the White Mountains. Young shoots reddish or
purplish olive-green deepening to a dark copper bronze. New England and
westward, also cultivated.

[Illustration: B. alba.]

3. =Betula alba=, L. (EUROPEAN WHITE BIRCH.) Leaves ovate, acute,
somewhat deltoid, unequally serrate, often deeply cut, nearly smooth; in
var. _pubescens_ covered with white hairs. Fruit brown, cylindric,
drooping. A tree, 30 to 60 ft. high, with a chalky-white bark; from
Europe, extensively cultivated in this country, under many names, which
indicate the character of growth or foliage; among them may be mentioned
_pendula_ (weeping), _laciniata_ (cut-leaved), _fastigiata_ (pyramidal),
_atropurpurea_ (purple-leaved), and _pubescens_ (hairy-leaved).

[Illustration: B. lenta.]

4. =Betula lenta=, L. (SWEET, BLACK OR CHERRY BIRCH.) Leaves and bark
very sweet, aromatic. Leaves ovate or ovate-oblong, with more or less
heart-shaped base, very acute apex, and doubly and finely serrate
margin, bright shining green above, smooth beneath, except the veins,
which are hairy. Fruit 1 to 1 1/4 in. long, cylindric, with spreading
lobes to the scales. A rather large tree, 50 to 70 ft. high, with bark of
trunk and twigs in appearance much like that of the garden Cherry, and
not splitting into as thin layers as most of the Birches. Wood
rose-colored, fine-grained. Moist woods, rather common throughout; also
cultivated.

[Illustration: B. lutea.]