betulaceae
Monecious trees or shrubs. Leaves simple, alternate, straight-veined, petiolate, stipulate. Flowers usually in catkins with numerous, imbricate or separate scales subtending 1-3 flowers; perianth absent or small; staminate flowers with 2-10 stamens, anther sacs frequently separate, filaments short; pistillate flowers with 2 carpels stigmas and syles 2, ovary inferior, 2-locular, 4-ovulate. Fruit a 1-seeded nut samara.