Betulaceae p25 
flowers 1—4 in the axil of each scale; perianth adherent to the ovary or none; ovary 
1—2-celled; style 2-cleft or -divided; cells 1-ovuled. Fruit a nut or samara, flat or 
ovoid-globose, mostly |-celled and |-seeded. 
A. Leaves densely stiff-hairy making them velvety to the touch; pistillate inflorescence 
bud-like, 5—10 mm. long; fruit a nut, | cm. or more in diameter, solitary or 2-3 
in a group, each enclosed in a leafy involucre; shrub. CoryYLus (p. 123) 
AA. Leaves not densely stiff-hairy nor velvety to the touch; pistillate inflorescence 
ament-like or cone-like; fruits small, many grouped together in cones or aments, without 
involucre; shrubs or trees. 
B. Bark often cracking in the direction of the tree-circumference; lenticels elon- 
gated in the direction of the tree-circumference; winter buds covered by imbricate 
scales; stamens 2, bifid; pistillate aments solitary; scales of pistillate aments thin, 
3-lobed, deciduous soon after the nutlets. BETULA, (p, 1123) 
BB. Bark cracking up and down the tree or not at all; lenticels not elongated in 
the direction of the tree-circumference; winter buds enclosed by 2 scales; sta- 
mens 4, not bifid; pistillate aments or cones racemose; scales of pistillate aments or 
cones thick, entire or erose or 5-toothed, persistent, becoming woody. 
ALNUuS (p. 124) 
CORYLUS HAZEL 
Shrubs (ours) or small trees. Leaves wide, serrate or incised. Flowers subtended 
by scales, monoicous (ours). Staminate flowers | to each scale: perianth none: stamens 
4; filaments forked, each fork bearing | cell of an anther, the united part adherent to 
the scale. Pistillate flowers in clusters, 2 to each scale, each with a pair of bractlets 
which enlarge and enclose the nut at maturity; clusters small, oval, bud-like, not pendu- 
lous: perianth slightly projecting at tip of ovary: style short; stigma elongated. Fruit a 
nut, oblong or ovoid (ours), large, hard-shelled. (Gk. korys—a helmet; referring to the 
involucre.) W.C.E. (C. rostrata for our region.) 
C. californica Rose 
BETULA BIRCH 
Shrubs or trees; bark either smooth or cracking around the stem; buds scaly. Leaves 
serrate or dentate, sometimes also somewhat lobed. Flowers in aments: aments expanding 
before the leaves, scaly: staminate scales entire: pistillate aments erect or spreading; 
scales 3-lobed or entire, deciduous with the fruits. Flowers monoicous. Staminate flow- 
ers about 3 in the axil of each scale, subtended by 2 bractlets: perianth membranous, 
usually 4-toothed: stamens 2; filaments short, deeply 2-cleft, each fork bearing | anther- 
sac. Pistillate flowers |—3 on each scale: perianth none: ovary sessile, 2-celled; styles 
2, stigmatic at apex, mostly persistent. Fruit a nutlet or samara, small, flat, membranous- 
winged on each side, shorter than the scale. (The Latin name.) 
A. Branchlets not or very little warty-glandular. W.C. E. (B. piperi.) 
B. occidentalis Hook. (Western Birch) 
AA. Branchlets very much warty-glandular. 
B. Shrub or small tree, 3—-12 m. high; leaves sparsely pubescent; body of the fruit 
much narrower than the wings. E. (JB. fontinalis.) st 
; B. microphylla Bunge (Rocky Mountain Birch) 
BB. Shrub, |—3 m. high; leaves: glabrous; body of fruit as wide or wider than 
the wings. W.C. E. (B. hallii.) 
B. glandulosa Michx. (Peat-bog Birch) 
