120 BETULACEAE. 



ovary sessile, 2-celled; nut small, with a wing, shorter than the 

 bracts. 



Shrub; branchlets warty with rcsiniferous glands. B. glandulosa. 



Tree; branchlets pubescent, not warty-glandular. B. occidentalis. 



Betula glandulosa Michx. {B. hallii Howell.) Low shrub, about 1 m. 

 high; twigs glandular-warty; leaves orbicular or obovate, cuneate at base, 

 crenate-dentatc, 1-3 cm. long, glabrous on both sides. 



Common in sphagnum bogs. 



Betula occidentalis Hook. Tree 10-30 m. high, with gray or darker bark; 

 leaves ovate, acute or acuminate, punctate above with resiniferous glands, 

 pubescent beneath, somewhat doubly dentate, slender-petioled; fertile aments 

 cylindric, 3-4 cm. long, on slender peduncles. 



From the Skagit River northward on the shores and islands of Puget Sound 

 and Vancouver Island, British Columbia. Hardly distinct from the more 

 eastern B. papyrifera Marsh. Perhaps the largest of all the birches. 



148. CORYLUS. Hazelnut. 



Shrubs with broad thin serrate or incised leaves; staminate 

 aments sessile at the ends of the twigs of the previous season, 

 expanding much before the lea\es; staminate flowers one in the 

 axil of each bract, each of four stamens; calyx none; pistillate 

 flowers clustered at the ends of short branches of the season, 

 each composed of an incompletely 2-celled ovary adherent to a 

 calyx; nut wingless. 



Corylus californica (A. DC.) Rose. Tall shrub, 2-10 m. high; branchlets 

 pubescent; leaves oval or obovate, obscurely 6-10-lobed, serrate, subcordate 

 at base, pubescent; involucre bristly, united to the summit, prolonged beyond 

 the nut into a broad tubular beak; nut ovoid. 



In open woods, common. 



149. ALNUS. Alder. 



Trees or shrubs; leaves dentate or serrulate; buds few-scaled; 

 both kinds of flowers in aments, expanding before, with or after 

 the leaves, the staminate pendulous, the pistillate erect, clustered; 

 staminate flowers 3, sometimes 6, in the axil of each bract, 

 consisting of a mostly 4-parted perianth and 4 stamens, and sub- 

 tended by 1 or 2 bractlets; filaments short, simple; anther-sacs 

 adnate; pistillate flowers 2 or 3 in the axil of each bract, without 

 a perianth, but subtended by 2-4 minute bractlets; ovary sessile, 

 2-celled; styles 2; bracts woody, persistent, 5-toothed or erose; 

 nut small, compressed, wingless or winged. 



Tree; leaves rusty-pubescent beneath; cones longer than the 



peduncles. A. oregona. 



Shrub; leaves glutinous, nearly glabrous; cones shorter than 



the peduncles. A. sinuata. 



Alnus oregona Nutt. Red Alder. Tree, 10-20 m. high, with pale smooth 

 bark; twigs reddish-brown, somewhat pubescent when young; leaves ovate to 



