54 Flora of the Palouse Region 



S. rostrata Richardson. Much branched shrub, 2-5 m. tall; leaves oblong, 

 elliptic, acute or acuminate, crenulate or nearly entire, pale and downy be- 

 neath, green and puberulent above, strongly reticulate, 3-8 cm. long; 

 petioles short; stipules ear-shaped, usually falling quickly: aments on short 

 bracteate peduncles appearing with the leaves: staminate dense; the obtuse 

 scales pale, hairy: stamens 2; filaments glabrous: pistillate looser, the linear 

 scales pale and pink-tipped: capsules pubescent, long beaked, with sessile 

 stigmas, the slender pedicel equalling or exceeding the persistent scales. 

 Common along streams. 



S. COrdata Muhl. Shrub, 2-5 m. tall, with elongate branches: leaves ob- 

 long or oblong-lanceolate, acuminate, glandular-serrulate, rounded or cor- 

 date at the base, glabrous above, glaucous beneath, 4-8 cm. long: petioles 

 stout: stipules conspicuous, reniform: aments appearing with the leaves, on 

 leafy peduncles: staminate narrow, densely flowered, 4-6 cm. long, the black 

 hairy scales persistent: pistillate looser; capsules glabrous, the long pedicels 

 far exceeding the scales; style as long as the stigmas. Common along 

 streams. Our form is somewhat different from the typical plant as found in 

 the Atlantic States. 



S. lasiolepis Benth. Large shrub, 5-6 m. tall: leaves petioled, oblong or 

 oblanceolate, obliquely acute or acuminate, serrulate, shining green above, 

 densely glaucous and somewhat pubescent beneath: stipules rarely pres- 

 ent, triangular: aments appearing with the leaves: staminate cylindrical, 

 3-5 cm. long, short-peduncled; scales black, hair} - : stamens 2, the glabrous 

 filaments united at the base for half their length: pistillate aments small, 

 1-3 cm. long, on short leafy peduncles: capsules glabrous, short-pedicelled; 

 style about equalling the stigma. Along the Palouse at Pullman, infrequent. 



Family 19. BETULACEAE. 



Trees or shrubs: leaves alternate, petioled, simple; stipules early 

 falling away: flowers small, monoecious, in linear-cylindric, ob- 

 long or subglobose aments; staminate aments pendulous; pistillate 

 aments erect, spreading or drooping, spike-like or capitate: stam- 

 inate flowers 1-3 in the axil of each bract, with a membranous 

 2-4 parted calyx, or calyx none, and 2-10 hypogynous stamens: 

 pistillate flowers with or without a calyx adnate to the solitary 

 1-2 celled ovary; ovules 1-2 in each cavity: fruit a small, com- 

 pressed, or ovoid-globose, mostly 1 -celled and 1 -seeded nut or 

 samara; endosperm none. 



Stamens 2; filaments 2-cleft, each fork bearing an anther sac: fruiting bracts 

 3-lobed or entire. 84. BETULA. 



Stamens 4; anther-sacs adnate: fruiting bracts woody, erose or 5-toothed, 

 persistent. 85. alnus. 



84. BETULA. 



Aromatic trees and shrubs: leaves dentate or serrate: buds scaly: 

 both kinds of flowers in aments, expanding before and with the 

 leaves: the pistillate aments erect or spreading: staminate flowers 

 about 3 in the axil of each bract, with a membranous, usually 

 4-toothed perianth, and 2 stamens, and subtended by 2 bractlets: 



