62 FLORA OP THE YELLOWSTONE NATIONAL PARK. 



CALLITRICHACEJE. 



Callitriche verna, L. 



Upper Falls of the Yellowstone (Adams) . 



Callitriche autumnal! s, L. 



Submersed in ponds and sluggish streams up to 8000 ft. alt. Common. 



CERATOPHYLLACE^I. 



Ceratophyllum demersum, L. 



Frequent in sluggish streams and lake sloughs throughout up to 8500 

 ft. alt. 



URTICACE^I. 



TTrtica gracilis, Ait. 



Borders of woods. Slough Creek, 6600 ft. alt. ; East Pelican Creek, 

 8500 ft. alt. Rare. 



CUPULIPER^ES. 



Betula occidentals, Hook. 



Gardiner, 5300ft. alt. ; Cache Creek, 7000 ft. alt. Along streams. Rare. 



Betula glandulosa, Michx. 



Bogs from 7500-9000 ft. alt. Common. 



Alnus viridis, DC. 



Yellowstone Lake (Adams). 

 Alnus incana, Willd., var. virescens. 



Wooded slopes, Pebble Creek, 8500 ft. alt. Rare. 



SALICINEJE. 



Salix longifolia, Muhl. 



Mammoth Hot Springs, 6400 ft. alt. A form with generally smooth 

 capsules and scales. Not common. 



Salix cordata, Muhl., var. Mackenziana, Hook. 



Rescue Creek, Mt. Evarts, 7500 ft. alt. Rare. 



Salix glauca, L. (a form). 



Bogs and along streams, from 6500-8500 ft. alt. Frequent. 



Salix glaucops, Anders. 



Subalpine, Mt. Washburne, 9000 ft. alt. 



Salix desertorum, Richards, var. Wolfli, Bebb. 



Bogs and streams, common throughout, up to 8500 ft. alt 



Salix arctica, R. Br., var. petraea, Anders. 



Alpine slopes and summits. Frequent. 



