418 BETULACEAE 
ra L. Tree becoming 30 m. tall, the younger bark silvery or yellow: 
leaf- blades ig -ovate, 3-6 cm, long, bro oadly cuneate at the base, more or 
less un entose beneath except ‘in age: 
stam e ame nis with suborbicular bracts: 
n us *pistillat aments 3—4 cm. long, less 
than 1 em. thick, the bracts 6-7 mm. long, 
tonno wing of the fruit reniform, 
eiliate.—(RIVER-BIRCH. RED- . W - 
IRCH.)—Swam s and stream-banks, vari- 
ous Pima eet uaa: Ridge, N Fla. to 
Tex., Minn., and Mas 
i 
26. 
^. 
NW. 
Vet: 
2. B. cordifolia Regel. Tree 10 m. tall or 
less, the young bark white or whitish: 
leaf-blades ovate to triangular-ovate, 4-8 
te or short-acuminate, doubly 
3:39, 
x A y 
* 
"ert 
2 
I 
aments with broadly ovate braets: pale pistillate aments 2.5-5 em. long, 
acd or ps bracts 5.5-6.5 mm. long, glabrous or obscurely pubes- 
ruit e eciliate. —Cool woods, Blue Ridge, N. C., 
nc aon poles N N. Y. to Minn. and Newf. 
B. lenta L. Tree becoming 25 m. tall, x bark e leaf-blades ovate, 
elliptie- orate, or ee pg edi 4-12 em. long, rounded or cordate at the 
base, si ben an staminate nt with ovate eus 
mature pistillate es 15S e . long, over 1 cm. thick, the bracts 5-6 mm. 
long and m or nearly a wide, mcr pom ous: wing of the fruit tri- 
angular-obova Or died not ciliate.—(S'WEET-BIRCH. |. .CHERRY-BIRCH. 
BLACK-BIRCH. gens M GANY-BIRCH.)—-Woods and hillsides, c 
ous D in Coastal Plain only N, Ga. to Ala., Minn., and Newf.— 
bark c an essential oil similar to that of wintergreen, and is distilled 
with pe in Por to secure it on a commercial s 
4. B. allegheniensis Britton. Tree becoming 30 m. tall, E bark —— ish or 
silvery: leaf-blades diu to elliptie-ovate, 5—10 em. long, rounde d or cordate 
at the base, pubescent on the nerves beneath: He odes with eos or 
oval-ovate bracts: ul pistillate aments 1.5—2.5 cm. long, very stout, the 
bracts 7-9 mm. long, quite or fully a side ae wing of the fruit pid 
obovate. [B. lutea (Fl. SE. U. S.) ]—(SOUTHERN YELLOW-BIRC Y- 
oe —Rich, often rocky woods, Blue Ridge and more northern pu 
o Man. and Newf. 
ALNUS [Tourn.] L. Shrubs or trees, the bark astringent. Stami- 
nate oe with 3-6 stamens, the anther-sacs connected. Bracts of the pis- 
tillate aments not lobed, woody and spreading at maturity.—About 15 species, 
natives of the Northern Hemisphere and the Andes. The bark yields tannic 
acid.—ALDERS. 
Aments flowering before or after the leaves develop: nut wingless, merely margined. 
1. A. rugosa. 
Aments flowering as the leaves develop: nut winged. 2. A. Alnobetula. 
1. A. osa (Du Roi) Spreng. pum or tree, becoming 13 m. tall: leaf- 
blades “thickish, obovate or oval, em. long: mature ae aments 
