Spring Flora of Oklahoma 
21 
FAMILY 11. BETULACEiE. Birch Family. 
Trees or shrubs with alternate, simple, petioled leaves, 
with usually deciduous stipules. Flowers monoecious in 
cylindrical or sub-globose aments. Staminate aments 
drooping. Flowers 1-3 in the axil of each bract. Calyx 
none or membranous and 2-4-parted. Stamens 2-10, dis¬ 
tinct. Calyx none or membranous and 2-4-parted. Sta¬ 
mens 2-10, distinct. Pistillate aments drooping, spread¬ 
ing, or erect and spike-like. Ovary solitary, 1-2-celled. 
Ovules 1-2 in each cell. Fruit a 1-celled nut or a key. 
Staminate flowers solitary in the axil of each bract, 
destitute of a calyx; pistillate flowers with a calyx. 
Fruiting bractlet flat; 3-cleft and incised. 
I. Carpinus. 
Fruiting bractlet bladder-like, closed, membranous. 
II. Ostrya. 
Staminate flowers 3-6 together in the axil of each bract, 
with a calyx; pistillate flowers without a calyx. 
Stamens 2; filaments 2-cleft; fruiting bracts 3- 
lobed or entire, deciduous III. Betula. 
I. CARPINUS L. 
Trees with thin, straight-veined leaves, primary veins 
terminating in the larger teeth. 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. Pistillate flowers in small terminal aments, 
2 to each bract, consisting of a 2-celled ovary adnate to a 
calyx and subtended by flat, persistent bractlet, foliaceous 
and lobed, or incised in fruit. Fruit a small, angular nut. 
1. Carpinus caroliniana Wialt. American Hornbeam. Leaves 
ovate-oblong, pointed, sharply double-serrate, soon nearly smooth. 
Bractlets 3-lobed, halberd-shaped, sparingly cut-toothed on one side, 
acute. 
In moist woods land along streams. April-May. Eastern part 
of the state. % 
