506 BETULACEAE. 
Family 6. BETULACEAE Agardh, Aphor. 208. 1825. 
BircH FAMILy. 
Monoecious or very rarely dioecious trees or shrubs, with alternate petioled 
simple leaves, and small flowers in linear-cylindric oblong or subglobose aments. 
Stipules mostly fugacious. Staminate aments pendulous. Staminate flowers 
1-3 together in the axil of each bract, consisting of a membranous 2—4-parted 
calyx or none, and 2-10 stamens inserted on the receptacle, their filaments dis- 
tinct, their anthers 2-celled, the anther-sacs sometimes distinct and borne on the 
forks of the 2-cleft filaments. Pistillate aments erect, spreading or drooping, 
spike-like or capitate. Pistillate flowers with or without a calyx adnate to the 
solitary 1-2-celled ovary; style 2-cleft or 2-divided; ovules 1-2 in each cavity of 
the ovary, anatropous, pendulous. Fruit a small compressed or oyoid-globose, 
mostly 1-celled and 1-seeded nut or samara. Testa membranous. Endosperm 
none. Cotyledons fleshy. Radicle short. 
Six genera and about 75 species, mostly natives of the northern hemisphere. 
Staminate flowers solitary in the axil of each bract, destitute of a calyx; pistillate flowers with a calyx. 
Staminate flowers with no bractlets; pistillate aments spike-like; nut small, subtended by or 
enclosed in a large bractlet. 
Fruiting bractlet flat, 3-cleft and incised. 1. Carpinus. 
Fruiting bractlet bladder-like, closed, membranous. 2. Ostrya. 
Staminate flowers with 2 bractlets; pistillate flowers 2-4, capitate; nut large, enclosed by a leafy 
involucre. 3. Corylus. 
Staminate flowers 3-6 together in the axil of each bract, with a calyx; pistillate flowers withouta calyx. 
Stamens 2; filaments 2-cleft, each fork bearing an anther-sac; fruiting bracts 3-lobed or entire, 
deciduous, 4. Betula. 
Stamens 4; anther-sacs adnate; fruiting bracts woody, erose or 5-toothed, persistent. 5. dA/nus. 
1. CARPINUS L. Sp. Pl. 998. 1753. 
Trees or shrubs, with smooth gray bark, furrowed and ridged stems and straight-veined 
leaves, the primary veins terminating in the larger teeth. Aments expanding before the 
leaves. Staminate aments linear-cylindric, sessile at the ends of short lateral branches of 
the preceding season, their flowers solitary in the axil of each bract, consisting of 3-12 sta- 
mens; filaments short, 2-cleft, each fork bearing an anther-sac. Pistillate flowers in small 
terminal aments, 2 to each bract, consisting of a 2-celled ovary adnate to a calyx and sub- 
tended by a flat persistent bractlet, which becomes much enlarged, foliaceous and lobed or 
incised in fruit, the bracts deciduous; style slender or almost none; stigmas 2,subulate. Nut 
small, ovoid, acute, borne at the base of the large bractlet. [The ancient name. ] 
About 12 species, natives of the northern hemisphere, only the following American. 
1. Carpinus Caroliniana Walt. American Hornbeam. Blue Beech. 
Water Beech. (Fig. 1207.) 
Carpinus Caroliniana Walt. F1. Car. 236. 1788. 
A small tree, with slender terete gray twigs, 
attaining a maximum height of about 4o° and 
a trunk diameter of 24°. Leaves ovate-ob- 
long, acute or acuminate at the apex, sharply 
and doubly serrate all around, rounded or 
subcordate at the base, somewhat inequilat- 
eral, 2'4’-4’ long, 1-114’ wide, green on both 
sides, glabrous above, slightly pubescent on 
the veins beneath, petioles very slender, 4//— 
7’’ long; staminate aments 1/-1 4 long, their 
bracts triangular-ovate, acuminate, puberu- 
lent; anther-sacs villous at the summit; bract- 
let of the pistillate flowers 3-lobed at the base, 
firm-membranous, strongly veined and about 
‘ long when mature, its middle lobe lanceo- 
late, acute, 2-4 times as long as the lateral 
ones, incised-dentate on one side, often 
nearly entire on the other; nut somewhat 
compressed, 2’’ long. 
In moist woods and along streams, Nova Sco- 
tia to Ontario and Minnesota, south to Florida 
and Texas. W Wood very hard and strong, durable, light brown; weight per cubic foot 45 lbs. April-— 
May, the fruit ripe Aug.—Sept. 
