22 
Spring Flora of Oklahoma 
II. OSTRYA (Micheli) Scop. 
Trees similar to the Hornbeams, the primary veins of 
the leaves simple or forked. Staminate aments sessile at 
the ends of brarichlets of the preceding season, flowers 
solitary in the axil of each bract. Pistillate aments small, 
terminal, erect, the flowers 2 to each bract, subtended by 
a tubular, persistent bractlet which enlarges into a mem¬ 
branous, nerved, bladder-like sac in fruit. Fruit a small, 
pointed, smooth nut. Mature pistillate ament hop-like. 
1. Ostrya virginiana (Mill.) Willd. Ironwood. Hop Hornbeam. 
Leaves oblong-ovate, taper-pointed, very sharply double-serrate, 
downy beneath, with 11-15 principal veins. Buds acute. Involucral 
sacs bristly-hairy at the base. 
In rich woods. April-May. Eastern part of the state. 
III. BETULA (Tourn.) L. 
Trees with slender, aromatic twigs, and thin, usually 
straight-veined leaves. Staminate aments drooping, flow¬ 
ers usually 3 in the axil of each bract. Stamens 4, short. 
Anthers 1-celled. Pistillate aments erect, flowers 2 or 3 
in the axil of each bract. Ovary sessile, 2-celled. Styles 
2. Bracts 3-lobed. Perianth none. Nut broadly winged. 
1. Betula nigra L. River Birch. Red Birch. A medium-sized 
tree with reddish-brown bark. Leaves rhombic-ovate, acute at the 
apex, acute or obtuse at the base, sharply and doubly serrate, white- 
downy below, becoming smoother with age, petioles short. Staminate 
catkins 2'-3' long. Pistillate catkins l'-l%' long, peduncles short, 
bracts nearly equally 3-cleft, w T ooly. 
Borders of streams, rivers and in swamps. April-May. 
FAMILY 12. FAGACEZE. Beech Family. 
Trees or shubs. Leaves alternate, simple, pinnately 
veined. Stipules deciduous. Flowers monoecious, the 
staminate in heads, or in drooping, spreading, or erect 
catkins. Calyx minute. Petals none. Stamens 4-20. Pis- 
