,) 1 
Aros (“ome - Atoka 
Alnus L,. Alder, 
Trees and shrubs. Perianth wanting in the pistillate mene Baw 
flowers, 4-parted in the ptaminate. Staminate flowers commonly 5 in the exil 
of each bract; stamens 4¢persistent, cuneiform, equally 4-lobed at the apex, 
the under surface provided with MBP veudequal appendage. Nutlet winged. 
iy 
O Leaves and twigs and budscales glabrous and somewhat 
4 sticky J, Ae sinvata 
oO Leaves, twigs and budscales pubescent 
A Leaves prevailingly double toothed; mature 
"cones" 12-14 mn. long, on peduncles mostly 
4-5 mm. long 2.A- tenuifolia 
—— 
& Leaves prevailingly single toothed, the teeth 4 
usually less than 1 mm. tall; mture gee 
iLreones" 8-10 mme long, on peduncles mostly 
-8 mm. long 9. Ae rhombifolia cs 
————_ 
1. Ae sinuata (Regel) Rydb. —-—___sShrubby, rarely an erect tree with us, 
commonly in clumps, the stems partly reclining on the ground, 2-4 m. tall, 
10-20 cm. in diameter; young bark smooth, olivaceéus, older bark grey, lenticels 
scattered, prominent, brownish, ovate, vertical, 2-4 mm. long; bud scales 
glabrous, resinous; branchlets resinous, shining; leaves 5-15 cm. long, rather 
broadly ovate, obtuse or somewhat acute, obliquely rounded at the base, 
sharply serrate, less often sinuately doubly serrate, upper surface glabrous, 
polished, lower surface sub-resinous, glandular, at least in the younger leaves, 
veins hairy in the angles; petioles 1-2 cm. long, glabrous; stipules oblong- 
lanceolate, recurved and soon deciduous, resinous; staminate catkins 10-12 cm. 
long, rhachis puberulent, calyx lobes rounded, shorter than the Stamens; 
pistillate catkins commonly 6-8 in a terminal cluster, oval when mature, 10-15 
mme long, the scales subentire, peduncles slender, glandular, commonly 1-1.5 cm. 
long, 1 mm. in diameter; nutlets oblanceolate in outline, 2-2.5 mn. long, 
each wing as wide or wider. ———__—_-»>(A. sitchensis Sargt.). 
Throughout our ranze, frequent in young burns, persisting however only ' 
in stream bottoms or on springy subalpine slopes, here forming commnities. tana hee 
sometimes several acres in extent; abundant from 3000-62300 feet. i 
ee 
