BETULACEAE (BIRCH FAMILY) 139 



Ascending, 3-9 dm. high; leaves long-villous beneath . . . 32. S. vestita. 

 Creeping, 0.3-1 dm. high; leaves glabrous beneath. 



Leaves 1.5-2.5 cm. long; aments many-flowered . . . . 33. S. saximontana. 



Leaves 7-1 2 mm. long; aments few-flowered ..... 34. S. nivalis. 



32. Salix vestita Pursh, Fl. Am. Sept. 2: 610. 1814. A shrub with rather 

 stout, light brown to yellowish, glabrous, angular twigs: leaves elliptic to 

 oblong-obovate or suborbicular, rounded to retuse at the apex, acute to obtuse 

 at the base, 3-4.5 cm. long, 2-3.5 cm. wide, obscurely crenulate, deep green 

 and glabrous above, clothed beneath with long white silky hairs, especially 

 on the midrib and veins; petioles 2-10 mm long: buds large, obtuse, light 

 brown: aments on villous peduncles; the staminate linear, 2-3.5 cm. long, 

 0.5 cm. wide; pistillate aments 2 cm. long, 1 cm. wide; scales oblong-ovate, 

 tomentose: capsules ovate-conic, 4-5 mm. long. (S. Fernaldii Blankinship, 

 Mont. Agr. Coll. Sci. Studies Bot. 1: 46. 1905.) Among rocks, not com- 

 mon; eastern Oregon and Montana to British Columbia and Alberta. 



33. Salix saximontana Rydb. Bull. N.Y. Bot. Card. 1: 261. 1899. Densely 

 caespitose and much branched, 3-6 cm. high: leaves elliptic-oblong to sub- 

 orbicular, obtuse or abruptly acute at the apex, acutish to rounded at the 

 base, 1.5-2.5 cm. long, 1-1.5 cm. wide, light green above, glabrous through- 

 out, margin entire and revolute: aments 1-2 cm. long, many-flowered; scales 

 broadly obovate, obtuse or rounded at the apex, cuncate at the base, yellowish, 

 nearly glabrous: capsules 3-4 mm. long, densely white-tomentose. S. retic- 

 ulata. (S. aemulans v. Seemen, 1. c. 28.) Alpine summits, 3,000 m. altitude 

 and upward; southern Colorado to Montana and west to California and Oregon. 



34. Salix nivalis Hook. Fl. Bor. Am. 2: 152. 1839. Scarcely 2 cm. high, 

 from buried stems: leaves elliptic, oblong-obovate, or suborbicular, acute, 

 obtuse or retuse, 7-12 mm. long, 4-8 mm. wide, green and shining above, 

 margins entire and revolute; petioles 2-7 mm. long, yellowish: aments globose 

 or oblong, 3-6-flowered, 1 cm. or less in length; scales oblong-obovate, obtuse, 

 yellowish, nearly glabrous: capsules 2.5-3 mm. long, tomentose. Alpine 

 summits; Montana to Alberta and westward. 



29. BETULACEAE Agardh. BIRCH FAMILY 



Trees or shrubs, with alternate simple leaves and deciduous stipules, and 

 monoecious flowers in aments, the staminate pendulous. Staminate flowers 

 1-3 in the axil of each bract. Calyx membranous and 2-4-parted, or wanting. 

 Stamens 2-10, the filaments sometimes dichotomous above with an anther cell 

 on each branch. Pistillate aments spike-like or capitate, with or without a 

 calyx, adnate to the solitary 1-2-celled ovary. Fruit a small 1-seeded nut, 

 with or without an involucre. 



Pistillate flowers with a calyx; nut inclosed in a large thick involucre . . 1. Corylua. 

 Pistillate flowers without a calyx; nut naked, often winged. 



Stamens 2; filaments bifurcate; nutlets winged ...... 2. Betula. 



Stamens 4; filaments not forked; nutlets not winged . . . . .3. Alnus. 



1. CORYLUS L. HAZELNHT 



Shrubs with double-toothed leaves, flowering in early spring. Sterile 

 aments single or fascicled, from scaly buds of the axils of the preceding year; 

 the fertile terminating early leafy shoots. Sterile flowers in drooping cylindri- 

 cal aments, destitute of a true calyx, consisting of several stamens included 

 under and more or less adnate to a bract; anthers 1 -celled. Fertile flowers in a 

 scaly bud or ament, two under each fertile bract, each with 1 or more bractlets 

 which form a foliaceous involucre to the large bony nut. 



1. Corylus rostrata Ait. Hort. Kew 3: 364. 1789. Shrub 6-16 dm. high: 

 leaves ovate or ovate-oblong, somewhat heart-shaped, abruptly pointed: in- 



