BETULACEAE. 97 



2. Betula glandulosa Michx. In bogs from Greenl. to Alaska, N. H., Colo, 

 and Ore. Alt. 9000-11,000 ft Middle Park; Argentine Pass; Cameron Pass; 

 mountains above Como; Twin Lakes; Seven Lakes; Blue River; Ironton 

 Park, nine miles south of Ouray ; Ruxton Park ; head of Muddy River, Mid- 

 dle Park; Pike's Peak; Tennessee Pass; Silverton; Breckenridge ; between 

 Como and Boreas; bank of the Big Muddy; western Gunnison Co.; Eldora 

 to Baltimore. 



2. ALNUS Gaertn. ALDER. 



i. Alnus tenuifolia Nutt. (A. incana virescens S. Wats.) Along streams from 

 Mont, to Alaska, N. M. and Calif. Alt. 6000-10,000 ft. Mountains between 

 Sunshine and Ward; Ojo; Turkey Creek and tributaries; canon, Idaho 

 Springs ; Cucharas Valley, near La Veta ; Hermosa ; near Pagosa Peak ; head- 

 waters of Pass Creek ; Larimer Co. ; Bob Creek, West La Plata Mountains ; 

 Red Mountain, south of Ouray; Lower Boulder Canon, Boulder Co.; Par- 

 lin; Colorado Springs; Black Canon of the Gunnison; Rist Canon; foot- 

 hills near Fort Collins ; Steamboat Springs ; Dolores. 



Family 37. CORYLACEAE Mirbel. HAZEL-NUT FAMILY. 

 i. CORYLUS L. HAZEL-NUT. 



i. Corylus rostrata Ait. In thickets and open woods and on hillsides from 

 N. S. to N. D., Ga. and Colo. Alt. 1200-8000 ft. Lower Boulder Canon, 

 Boulder Co.; North Cheyenne Canon; foot-hills, Larimer Co.; Rist Canon; 

 gulch west of Soldier Canon ; vicinity of Arthur's Rock. 



Family 38. FAGACEAE Drude. BEECH FAMILY. 



i. QUERCUS L. OAK. 



Leaves lobed or divided, not evergreen ; lobes rounded, obtuse or acute, but not 



spinulose-tipped. 

 Leaves bright green, early deciduous. 



Mature leaves softly pubescent, almost velvety beneath, deeply divided. 



i. Q. utahensis. 

 Mature leaves glabrate, puberulent or somewhat pubescent, but not velvety 



beneath. 



Cup flat, covering less than l /4 of the acorn. 2, Q. Vreelandii. 



Cup hemispheric, covering y$ to *^> of the acorn. 

 Acorns barrel-shaped, obtuse. 



Mature leaves very thin, glabrate beneath or puberulent only on the 

 veins ; cup covering about l / 2 of the acorn ; scales of cup thin. 



3. Q. leptophylla. 

 Mature leaves firm, puberulent beneath, cup covering about I /T, of the 



acorn ; scales of cup thick, corky. 

 Leaves mostly oblong in outline, lobed halfway to the midrib or 



less, rather dull. 4. Q. Gimnisonii. 



Leaves obovate in outline, divided deeper than halfway to the mid- 

 rib, very shining above. 

 Lobes of the leaves broadly oblong, rounded at the apex. 



5. Q. nitescens. 

 Lobes of the leaves ovate or triangular, acute. 



6. Q. novomexicana. 



