204 * BETULACEAE 



7. B. fontinalis Sarg. A tree occasionally 10-12 m. high, often growing 

 in clumps and shrub-like; blades sharply double-serrate, entire towards the base, 

 soon glabrous, 2-5 cm. long; staminate aments 5-7 cm. long, several; pistillate 

 aments 2-3 cm, long; termmal lobe of the bractlets lanceolate, decidedly longer 

 than the lateral ones. B, occidentalis Nutt., not Hook. Mountain Birch, 

 ^^^^^tP^^^^' Swamp Birch, Black Birch. River banks: Sask.— Neb.— 

 N.M.— Utah— Calif.— B.C.— Yukon. Plain— Mont. My-Je. 



8. B. montanensis Butler. A large tree; leaf-blades 4-6.5 cm. long, thick 

 and farm, sUghtly lobed, finely serrate, glabrous above, conspicuously hairy 

 beneath; frmtmg aments 2.5-3.5 cm. long; bractlets 5-7 mm. long: middle lobe 

 triangular-lanceolate, acute. Lake shores: Mont. Submonf, 



9. B. Sandbergii Britton. A shrub or shrub-like tree; leaf-blades up to 6 

 cm. long, thick, firm, dull bronze-green above, paler and sparsely hairy beneath, 

 rhombic-oyate or oval, acute at both ends; fruiting aments 2-4 cm. long, slender- 

 stalked; middle lobe of the bractlets longer than the ascending rounded lateral 

 ones. Black Birch. Swampy places: Sask.— Minn.— Mont. Plain. 



e^ui ?' EIrodiana Butler. A low shrub; twigs slender, red-brown or gray; 

 leaf-blades 1-3 cm. long, 1-2 cm. wide, oval or rhombic, rarely ovate or obovate, 

 often suborbicular, shining, dark green above, duU green and reticulate beneath; 

 fruiting aments 10-15 mm. long, 6-8 mm. thick, cyUndric or ellipsoid. Swampy 

 places: w Mont. SubmonL 



^^'i ^- °^0''3'ta Butler. A coarse shrub; branchlets red-brown, becoming 

 gray; leaf-blades 2-4 cm. long, thick, firm, dark, shining above, paler and dull 

 beneath, serrate or crenate-serrate; fruiting aments cyhndrical or oval, 2-2.5 

 cm. long, 6-8 mm. thick; middle lobe of the bractlets long, ovate or triangular, 

 obtuse, or acutish; lateral lobes obliquely rhombic. River banks: w Mont. 

 oubmont. 



12. B. crenata Rydb. A shrub 2.5-4.5 m. high; branches puberulent and 

 dish when young; leaf-blades slightly pubescent when young, oval or elliptic, 



1-6 cm. long, 8-20 mm. wide, crenate, dark green, shining, reticulate-veined 

 above; pistillate aments 12-18 mm. long, about 6 mm. thick; terminal lobe of 

 bractlets oblong or elhptic, obtuse or rounded at the apex; lateral lobes ascending, 

 obliquely ovate or rhombic, obtuse; nut oval, nearly 2 mm. long; wings of nearly 

 the same width. Lake banks: w Mont. SubmonL Je. 



13. B. glandulifera (E. Regel) Butler. A shrub 1-5 m. high; leaf-blades 

 dentate-crenate, with rounded-ovate or on the vigorous shoots triangular teeth, 



reddish 



5-3 



reddish green beneath; pistillate aments 1-2 cm. lone, 6-7 



...^v^v.^vo ^x^^^yj^c luuco ail uuiuiig aiiu oDiuse ac tne apex, ot nearly the same 

 length; wing one-fourth to one-half as wide as the oval nut. B. mimila glanduli- 

 fera E. Regel. Boggy places: Ont.— Wis.— Minn.— Sask. Plain— SubmonL 

 My. 



14. B. glandulosa Michx. A shrub 0.3-2 m. high; twigs brown and 

 densely glandular-resiniferous; leaf-blades 1-2.5 cm. long, rounded at both ends 

 or sometimes acutish at the base, bright green above, paler beneath; staminate 

 aments usually solitary, 1-1.5 cm. long; pistillate aments 1-2.5 cm. long, 4^5 

 mm. thick; bractlets glabrous; lobes oblong, obtuse, the lateral ones shorter, 

 spreadmg, ascending and curved upward; wing of the samara very narrow. 

 Bog Birch, Scrub Birch Wet places: Greenl.— Me.— Minn.— Colo.— Ore.— 

 Alaska. SubmonL— Subalp. Je-Jl. 



2. ALNTJS (Toum.) Hill. Alder. 



Shrubs or trees, with astringent smooth bark. Staminate aments drooping; 

 calyx uregularly lobed; stamens as many as the lobes and opposite to them; 

 anthere mtroree. Pistillate aments ovoid or oblong, cone-like; bracts subtend- 

 mg 2 flowers becoming woody, truncate or lobed at the apex, persistent. Fruit 

 minute, nut-like, Tvmged or wingless, with thin outer coat. Seeds soUtarv. 



