616 
MONOECIA POLYANDRIA. 
BETULA. 
Masculi. Amentum 
imbricatum, squamis 
peltatis, trifloris. Ca- 
lyx squama. Corolla 
0. Stamina 10 — 12. 
Foeminei . Amentum 
imbricatum. Calyx 
squama biflora. Co- 
rolla 0. Semen 1, ala- 
tum. 
Gen. Pl. 1419. 
Sterile florets. A- 
ment imbricate, scales 
peltate, thrCe-flowered. 
Calyx a scale. Corol- 
la 0. Stamens 10 — 12. 
Fertile florets. A- 
ment imbricate. Calyx 
a scale 2-flowered. Co- 
rolla 0. Seed 1, wing- 
ed. 
1. Nigra. Lin. 
B. foliis rhombeo- 
ovatis, duplicato-serra- 
tis, acutis, subtus pube- 
scentibus, basi integris; 
amends foemineis ova- 
tis, squamis villosis, 
Iaciniis linearibus ae- 
qualibus. 
Leaves rhomboidal, 
ovate, doubly serrate, 
acute, pubescent under- 
neath, entire at base; 
fertile aments ovate, 
the scales villous, the 
segments linear equal. 
Sp. pl. 4. p. 464. Pursh, 2. p. 621. Nutt. 2. p. 218. 
B. Alba, Walt. p. 231? 
B. Lanulosa, Mich, 2. p. 181. 
B. Rubra, Mich. arb. for. 2. p. 142. 
A tree growing commonly 30 — 40 feet, and from 1 — 2 feet in diameter, 
though sometimes attaining a much greater size; the trunk covered with a 
smooth scaly bark, the branches long and flexible. Leaves on short peti- 
oles, ovate, acuminate, somewhat angled and acutely serrate, very pubescent 
underneath when young. Fruit in small oval aments, scales 3-cleft villous, 
the segments equal. 
Grows along the margins of rivers whenever the soil is wet and sandy. 
The wood, I believe, is very little used in the Southern States. 
Flowers March. 
