BIRCH FAMILY. 509: 
Betula papyrifera Marsh. Arb. Am. 19. 1785. 
Betula papyracea Ait. Hort. Kew. 3: 337-17 
A large forest tree with maximum height of 
about So° and trunk diameter of 3°. Bark, except 
of the young wood, peeling in thin layers. Leaves 
ovate, acute or acuminate, dentate and denticulate, 
subcordate, truncate or obtuse at the base, dark 
green and glabrous above, glandular and pubes- 
cent on the veins beneath, slender-petioled, 1}2/— 
4%’ long, 1/-3’ wide; petioles 1’-14’ long; stam- 
inate aments 2/-4’ long; pistillate aments cylin- 
dric, slender-peduncled, 1/-2’ long, {’—!2’ in dia- 
meter in fruit, spreading or somewhat drooping; 
fruiting bracts 2//-3’’ long, puberulent or ciliate; 
nut narrower than its wings. 
Newfoundland to Alaska, northern Pennsylvania, 
Michigan and Washington. Wood hard, strong, red- 
dish-brown; weight per cubic foot 37 lbs. The chalky- 
white outer bark interesting to tourists. April-May. 
Betula papyrifera minor Tuckerm. Am. Journ. Sci. 45: 31. 1843. This is a low bushy form, 
occurring on the higher mountains of New England and northern New York. 
3. Betula occidentalis Hook. Western 
Red Birch. (Fig. 1213.) 
Betula occidentalis Hook. Fl. Bor. Am, 2: 155. 1839. 
A tree, attaining a maximum height of about 40° 
anda trunk diameter of 114°, the bark smooth, dark 
bronze, the twigs gray-brown, warty. Leaves 
broadly ovate or nearly orbicular, acute or obtuse at 
the apex, sharply serrate, rounded or obtuse at the 
base, short-petioled, glabrous on both sides or spar- 
ingly pubescent on the veins beneath, 1/—2’ long; 
petioles slender, 2’/-6’’ long; pistillate aments man- 
ifestly peduncled, cylindric, spreading or pendant, 
1/-1 4’ long, about 5’’ in diameter in fruit; fruiting 
bracts ciliolate, about 3/’ long, their lateral lobes 
ascending, usually shorter than the middle one; 
nut much narrower than its wings. 
Western Nebraska to British Columbia, California 
and New Mexico. Wood soft, strong, brittle, light 
brown; weight per cubic foot 38 lbs. April-May. 
4. Betula nigra I, River Birch. Red Birch. (Fig. 1214.) 
Betula nigra I,. Sp. Pl. 982. 1753. ~ 
A slender tree, sometimes go° high and the trunk ‘%\\~ 
2'%° in diameter; bark reddish or greenish-brown, 
peeling in very thin layers; twigs reddish. Young 
shoots, petioles and lower surfaces of the leaves tomen- 
tose; leaves rhombic-ovate, apex acute or obtuse, 
irregularly serrate or somewhat lobed, base cuneate, 
when mature dark green and glabrous above, pale and 
glabrous or somewhat tomentose beneath, 134/—3/ 
long; petioles 3/’-8’’ long; staminate aments mostly 
clustered in 2’s or 3's, 24%4’-34’ long; pistillate aments 
oblong-cylindric, spreading, peduncled, 1/-2’ long, 
5//-6’’ in diameter in fruit; fruiting bracts tomen- 
tose, about equally 3-lobed, 3/’-5’’ long; nut broadly 
obovate, wider than its wings, pubescent at the base. 
Along streams and lakes, Massachusetts to Iowa 
and Kansas, south to Florida and Texas. Wood hard, 
strong, brown; weight per cubic foot 36 lbs. The bark 
of the branches peels off in almost membranous layers. 
April-May. 
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