KEY TO IMPORTANT WOODY PLANTS 123 



8. Tall shrubs or small, straggly trees; bark gray brown and 

 smooth on young stems, reddish brown and scaly on old 

 trunks; pollen-producing catkins and seasonal twigs dull- 

 waxy-resinous, minutely ashy-hairy; last season's seed- 

 producing catkins commonly disfigured by disease; 

 "seeds" narrowly margined, scarcely winged; commonest 

 alder of e. Oreg., e. Wash. 



thinleaf (or mountain) alder (Alnus tenuifolia). 

 6. Seed-producing catkins somewhat conelike or tassellike, 

 stalked, single (sometimes clustered), erect or drooping at 

 tips of dwarf side twigs, not persistent except for their cen- 

 tral, erect or recurved stalks from which the 3-lobed papery 

 scales fall — either with or after shedding of the tissue-papery- 

 winged "seeds" (nutlets or samaras) ; next season's seed-pro- 

 ducing catkins hidden in the bud until leaves unfold in spring; 

 twigs slender, round, sparsely resin-dotted or densely warty 

 with resin glands when young, becoming smooth and marked 

 with pale pores (lenticels) ; pith compressed, somewhat 3-sided; 

 end buds lacking, stem tips dying back to topmost side buds 

 except on dwarf side twigs; buds only slightly resinous, to ){ 

 inch long, stalkless but sometimes appearing stalked at tips 

 of dwarf side twigs; bud scales at least 3, spirally overlapping; 

 leaf scars somewhat crescent-shaped; bundle traces 3; buds 

 and leaf scars in counterclockwise spiral on twigs; shrubs or 

 trees of moist sites, sometimes thicket-forming. 



birches {Betula spp.). 

 10. Bark shredding or separating into papery layers at base 

 of old trunks; seasonal twigs sparsely resin-dotted but not 

 warty with resin glands; seed-producing catkins rather 

 plump, soon drooping, their scales sometimes persistent 

 until late fall; trees to 60 or 90 feet high. 



paper birches (varieties of Betula papyrifera) . 

 1 1 . Seasonal twigs orange brown, with a few straggly white 

 hairs; bark of lower trunk warm brown, shredding to 

 show orange brown or creamy layers underneath; large 

 trees to 90 feet high; both sides of Cascades in n. Wash, 

 and on the Colville Indian Reservation, also in Blue 

 Mts., se. Wash.; not reported from Oreg. 



western paper birch (Betula papyrifera var. 



commutata). 

 11. Seasonal twigs finely hairy or almost hairless, reddish 

 brown to gray; bark of lower trunk dark silvery gray, 

 peeling to show purplish or whitish, shreddy layers 

 underneath; trees to 60 feet high, sometimes with clus- 

 tered trunks; rather rare, in Wallowa Mts. of ne. Oreg., 

 Blue Mts. of se. Wash. 



northwestern paper birch {Betula papyrifera var. 



subcordata). 



10. Bark not shredding or separating into layers as above; 



twigs densely warty with resin glands, minutely hairy 



under a lens: seed-producing catkins often erect; shrubs 



or small trees, often thicket-forming. 



