Northern Prairie Wildlife Research Center
Northeast Wetland Flora
Field Office Guide to Plant Species
Alnus crispa (Dryand. in Ait.) Pursh
- Family: Birch (Betulaceae)
- Flowering: June-August
- Field Marks: This species differs from other alders by its conspicuous winged nutlets and its
sessile winter buds.
- Habitat: Shores, bogs, usually in mountainous areas.
- Habit: Much branched shrub to 10 feet tall.
- Stems: Slender to stout, smooth or densely soft-hairy; winter buds sessile, tapering to a long point at the tip.
- Leaves: Alternate, simple, ovate to oval, pointed at the tip, usually slightly heart-shaped at the base, irregularly fine-toothed, smooth or densely soft-hairy, up to 5 inches long, with a stalk up to 1 inch long.
- Flowers: Male and female flowers borne separately but on the same plant, the male flowers 3 in a cluster and subtended by 4 or 5 bractlets, all in a slender spike up to 3 inches long, the female in 2-10 ovoid spikes in a cluster, each spike up to 1 inch long, with every two flowers subtended by a fleshy bract.
- Sepals: 3-5, minute, green, united to each other, or absent.
- Petals: 0.
- Stamens: 3-5.
- Pistils: Ovary inferior.
- Fruits: Many nutlets aggregated into a "cone," with each nutlet subtended by a woody bract, the nutlets conspicuously winged, 1/12-1/10 inch long.
- Notes: This species is called A. viridis by Gleason and Cronquist. The young flowers are concealed by the winter buds prior to the year they open. There is considerable variation in the amount of hairiness on the leaves and young twigs.
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