Contemporary Circumscription Compared with A Utah Flora 4th ed.

Bio430

Betulaceae

No differences

Key Features

Woody trees or shrubs, monoecious.  Leaves are alternate, have ephemeral (caducous) stipules, usually double-serrate margins, and are plicate (folded accordian-like) when young along their strongly parallel secondary veins.  Both male and female flowers occur in catkins, with the male inflorescences pre-formed in the fall so that they are apparent throughout the winter.  Female inflorescences appear as new vegetative buds expand, with the stigmas sometimes exerted through the bud scales before the rest of the bud opens.  The inferior ovary is 2 carpellate, 2 locular at has 2 ovules in each locule, but only one ovule typically matures to form a nut or nutlet, or samara subtended or enclosed by bracts.