Northern Prairie Wildlife Research Center
Western Wetland Flora
Field Office Guide to Plant Species
Alnus incana (L.) Moench
- Family: Birch (Betulaceae)
- Flowering: March-June
- Field Marks: This spring-flowering alder is distinguished by having the female flowers borne on drooping branches that are lower than the male flowering branches.
- Habitat: Along streams, in swamps.
- Habit: Sprawling or upright shrub up to 15 feet tall.
- Stems: Trunk and branchlets brown to blackish and marked with elongated, white lenticels.
- Leaves: Alternate, simple, ovate to oval to broadly elliptic, rounded to pointed at the tip, rounded or somewhat heart-shaped at the base, usually doubly toothed, more or less smooth.
- Flowers: Male and female flowers borne separately but on the same plant, each kind
arranged in clusters; male flowers usually 3 in a cluster, subtended by 4-5 small bracts; female
flowers in spikes, each pair of flowers subtended by fleshy bracts.
- Sepals: 3-5, united, greenish in the male flowers, absent in the female flowers.
- Petals: 0.
- Stamens: 3-5.
- Pistils: Ovary 1, apparently inferior.
- Fruits: Woody "cones" up to 1/2 inch long, with narrowly winged nutlets.
- Notes: The fleshy bracts subtending the female flowers form the woody scales of the "cone" in fruit. The nutlets are eaten by birds and mammals.
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