BIRCH FAMILY. 



2. Betula papyrifera Marsh. Paper or Cain. c Birch. (Fig. H 



'iclula papyrifera Marsh. Arb. Am. 19. 1785. 

 lift nla pafiyracea Ait. Hort. Kew. 3: 337. 1789. 



A large forest tree with maximum height of 

 about 80 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 

 ;! <. < 'ii and glabrous above, glandular and pubes- 

 cent on the veins beneath, slender-petioled, i^'- 

 4';.' long, I'-T,' wide; petioles J^'-i^' long; stam- 

 inate aments 2 / -4 / long; pistillate aments cylin- 

 ic, slender-peduncled, i / -2 / long, ^'-yi' in dia- 

 iter in fruit, spreading or somewhat drooping; 

 iting bracts 2 // -3 // long, puberulent or ciliate; 

 nut narrower than its wings. 



Newfoundland to Alaska, northern Pennsylvania. 

 Michigan and Washington. Wood hard, strong, rrd- 

 ('i>h-brown; weight per cubic foot 37 Ibs. The chalky- 

 white outer bark interesting to tourists. April-May. 



ma 

 drii 



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Betula papyrifera minor Tuckerm. Am. Journ. Sci. 45: 31. 1843. This is a low bushy form, 

 occurring on the higher mountains of New Kngland and nortlu-rn New York. 



3. Betula occidentalis Hook. Western 

 Red Birch. (Fig. 121;,. 



lictula occidentalis Hook. Fl. Bor. Am. 2: 155. 1839. 

 A tree, attaining a maximum height of about 40 

 anda trunk diameter of i^, 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, i'-2' long; 

 petioles slender, 2 // -6"long; pistil late aments man- 

 ifestly peduncled, cylindric, spreading or pendant, 

 I'-iJf' 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 3* !;-. April-May. 



4. Betula nigra L. River Birch. Red Birch. (Fig. 1214.) 



Betula nigra L,. Sp. PI. 982. 1753. 



A slender tree, sometimes 90 high and the trunk 

 2)4 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, 1%'-$' 

 long; petioles 3 // -8 // long; staminate aments mostly 

 clustered in 2's or 3's, 2^ / ~3^ / long; pistillate aments 

 obloug-cylindric, spreading, peduncled, i / -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 

 ami Kansas, south to Florida and Texas. Wood hard, 

 strong, brown; weight per cubic foot 36 Ibs. The bark 

 of the branches peels off in almost membranous layers. 

 April-May. 



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