58 



American Midland Naturalist Monograph No. 4 



1. Thinleaf Alder, Mountain Alder (Alnus tenuifolta Nutt.), fig. 

 13. — Shrub 6 to 15 feet high or sometimes a tree 20 to 25 feet high; bark 

 smooth, thin, grayish-brown; leaves egg-shaped, bluntly pointed at the tip, 



1 1/2 to 4 inches long, the margins coarsely 

 toothed or somewhat lobed and again 

 toothed, dark green and frequently gummy 

 above, paler below; male flowers borne in 

 long pendent clusters 1 to 3 inches long, 

 appearing before the leaves; cones about 

 1/3 to 1/2 irich long, brown when ripe, 

 borne in clusters of several near the ends 

 of the branches; fruits small seedlike nut- 

 lets with narrowly winged margins. 



Occurrence. — CRATER LAKE, occasional, 5,800 

 to 6,250 feet: Annie Creek at south entrance. 

 LASSEN, occasional. GLACIER, abundant alon;| 

 streams, 3,100 to 5,000 feet: along Middle Fork 

 of Flathead River at Belton; Lake McDonald; 

 St. Mary Lake near East Glacier Campgrounds. 

 YELLOWSTONE, occasional: near east entrance; 

 Tower Creek; Gardiner River; Yellowstone 

 River. GRAND TETON, occasional, 6,000 to 8,500 

 feet. ROCKY MOUNTAIN, common along streams: 

 Big TTiompson Canyon, 7,000 feet. MESA VERDE. 



Fig. 13. Thinleaf alder (Alnus 

 tenuifolia) . 



2. Speckled Alder (Alnus incana 



(L.) Moench.). — Tall shrub or small 



tree up to about 15 feet high; leaves 



broadly elliptic to egg-shaped, rather 



coarsely double-toothed, dark green 



above with impressed veins, rusty or 



whitish below and somewhat downy, at 



least on the veins; fertile catkins borne 



on short stout stalks, coming from naked 



buds formed the previous season, the 



flowers developing before the leaves; 



seed-like fruits wingless or with merely 



a narrow leathery margin. This is the 



species commonly found in swamps and 



along streams. 



Occurrence. — isLE royale, common: Mott 

 Island. 



3. Sitka Alder (Alnus sinuaia 

 (Regel.) Rydb.), fig. 14.— Similar to 

 mountain alder but the leaves finely 

 toothed and not, or scarcely, lobed; 



Fig. 14. Sitka alder (Alnus 

 sinuata). 



