Alnus serrulata - Smooth Alder

Sizes available: #1 (Trade gallon), perhaps fall, 2026

Basics: zones 4-9, sun to part shade, 10-20 feet high at maturity, 8-15 foot-wide canopy (multi-stemmed, suckering), catkins bloom March to April, both male and female on same plant, cones develop. Wants moist-wet mucky soil, but is okay with medium moisture, is clay tolerant, doesn't like a high pH.

Common names: Smooth Alder, Hazel Alder, Tag Alder, Common Alder, Black Alder, Brookside Alder

Family: Betulaceae

Origin/Distribution: eastern North America from Nova Scotia and New Brunswick south to Texas and Florida, Maine native

Habitat: moist places such as stream side, pond edge, riverbank, bog, ditch, low field. According to plants.usda.gov, Alnus serrulata can also grow on more well-drained sites.

More: This plant is monoecious and the female catkins develop into seed cones eaten by birds such as goldfinch and grouse. Pollen-rich catkins are also eaten by birds and small mammals and deer browse young twigs.  Alder thickets provide protective habitat for various birds. Branches of male catkins in the spring and female cones in the fall are handsome additions to flower arrangements. A thicket of alder is excellent erosion control and a nitrogen-fixer that can rehabilitate degraded sites. The stem bark of Smooth Alder has been used medicinally. The female flowers are wind-pollinated and this species can hybridize with A. incana. Alder takes well to strong pruning. Larval host for Papilio glaucus (Eastern Tiger Swallowtail), Polygonia faunus (Green Comma), Limenitis arthemis (White Admiral), and Nymphalis antiopa (Mourning Cloak) among others. According to the Ladybird Johnson Wildflower Center this alder makes for "picturesque habitat". Can be pruned hard to rejuvenate.

Source: whips from Cold Stream Farm, 2025

Image credit: Wikimedia Commons