BETULACEAE (Birch Family)
Plants trees or
shrubs, monoecious. Leaves alternate, short- to less commonly long-petiolate.
Leaf blades simple, pinnately veined, the margins toothed. Stipules scarious or
somewhat hardened, broadly ovate, mostly shed during leaf development.
Inflorescences of separate staminate and pistillate catkins (the pistillate
ones in globose clusters in Corylus). Flowers actinomorphic, imperfect.
Staminate flowers with calyces absent or of (1–)4(–6) minute,
scalelike sepals; corollas absent; stamens mostly 4–6, with a reduced,
nonfunctional pistil sometimes present. Pistillate flowers with calyces
rudimentary or absent; corollas absent; stamens and staminodes absent; ovary
inferior (but often appearing naked in the absence of perianth), with 2 locules
toward the base but often appearing 1-locular toward the tip, the placentation
axile. Styles 2 (sometimes united basally), each with a linear stigmatic region
toward the tip. Fruits nuts, nutlets, or samaras, surrounded by bracts and
often grouped into conelike infructescences. Six genera, 125–150
species, North America to South America, Europe, Asia.
Betulaceae form an important part of the woody vegetation in many parts of
Missouri. Many Betulaceae are tolerant of flooding and waterlogging, and they
are a common component of the woody cover on stream banks and wet bottomlands.
Other species dominate the woody understory in some Missouri forests. The seeds
of all of our species are eaten by birds and other wildlife.