| Family: | Betulaceae |
|---|---|
| Common name: | birch family [Zomlefer, pp. 176-179] |
| Diversity: | Worldwide: 6 genera; ~150 species U.S.: 5 genera PNW (Hitchcock & Cronquist): 3 genera |
| Flower -- Vegetative Features -- Economic Importance -- Flower Images-- Web Sites | |
| Flower | |
|---|---|
| K0 or 4 Co0 S2-20 | K0 Co0 P .GIF) |
| Sexuality: | unisexual, (plants monoecious) |
| Symmetry: | actinomorphic |
| Inflorescence: | cyme |
| Calyx (sepals): | present in some genera, separate |
| Corolla (petals): | absent |
| Androecium: | 2 to 20 stamens |
| Gynoecium: | bicarpellate, united, inferior ovary (=epigynous flower) |
| Fruit: | single-seeded nut or samara |
| Other features: | flowers are associated with bracts in pendant clusters called catkins, wind-pollinated |
| Vegetative Features | |
|---|---|
| Leaves: | alternate, simple with serrate margins and prominent pinnate veins, stipulate leaves deciduous |
| Life-history: | perennial |
| Habit: | trees and shrubs |
| Distribution & Ecology: | temperate regions of N. Hemisphere roots of Alnus associate with nitrogen-fixing bacteria |
| Some Northwest Genera: | Alnus alder Betula birch Corylus cornuta hazelnut, filbert |
| Economic Importance | |
|---|---|
| Crops: | Corylus cornuta hazelnut, filbert Alnus alder and Betula birch are sources of lumber |
| Ornamentals: | |
| Weedy and pest species: | |
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