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Weed Identification

hazel alder



Scientific Name

Alnus serrulata

Other Common Names:

smooth alder

Synonyms (former Scientific Names):

Alnus incana
Alnus noveboracensis


For streambank stabilization, smooth alder is best established as a bare-root or containerized seedling planted two feet apart within rows with rows two feet apart. It may be incorporated into a soil bioengineering system by planting at the toe of the bank just above any toe stabilization measures such as rip-rap, coir (coconut) logs, or fascines. On nonerosive streambanks it may be planted in two rows to provide toe protection. If this alder is planted for wildlife habitat improvement or wetland mitigation,planting should be done at a 5-10 foot spacing to allow for crown development and to optimize seed production.

Identifying Characteristics

Smooth alder is a nitrogen-fixing, thicket-forming shrub or small tree with dark, green foliage. It is a U.S. native. It is suitable for streambank stabilization because of its flexible stems and fibrous root system. A mature height of 8-12 feet may be reached in 10 years.Alders produce nitrogen for themselves by the activity of nitrogen-fixing bacteria located in root nodules. For this reason, it is not recommended for planting in areas where additional nitrogen might add to water quality problems. Smooth alder has about 400,000 seeds per pound.

Seed Fruit

Seed is produced in small cones with pollen contributed by birch-like catkins which bloom in mid-to late March.

Where Found

Smooth alder is native to the northeast. It occurs from southern Maine to northern Florida, west to southeastern Oklahoma, Missouri, and Illinois. It grows best in wet bottomlands and stream margins however it will also grow in well-drained upland areas. It is moderately shade and acid tolerant, but is weak-wooded and susceptible to wind and ice damage.

Life Cycle


Plant Type