Alnus serrulata (Smooth Alder)

Most attractive, Alnus serrulata (Smooth Alder) is a large, spreading deciduous shrub or small tree of pyramidal habit with a densely branched canopy. Its multi-stemmed trunks are covered with shiny gray-brown bark. The foliage of undulating, elliptic to obovate, glossy green leaves, 2-4 in. long (5-10 cm), turns yellow-brown in the fall. In early to mid-spring, long, pendant, pale yellow male catkins, 4 in. long (10 cm), dangle like Christmas decorations near the bare branch tips. The catkins release clouds of pollen that attract bees and other insects. Inconspicuous female flowers in the form of tiny red-purple tassels bloom in clusters at the twig tips. They are followed by small, dark brown, fruiting cones, 1 in. long (2.5 cm), containing winged seeds (nutlets). Resembling miniature pine cones, they persist on the twigs for up to a year for a unique and lovely display – to the delight of birds. Smooth Alder is a suckering plant forming thickets that become an effective choice for erosion control. Adaptable to drier soils as well as flooding, it is a great plant for naturalizing along stream banks, rivers, or pond margins. Smooth Alder fixes nitrogen and thus serves as a nutrient-giving pioneer in reclamation projects. An intermediate source of food for wildlife, Alders support 255 species of caterpillars as well as many sawfly larvae. This allows a grove of Alder to provide food and shelter for wintering birds, breeding birds, and migrant birds.

Smooth Alder is a favored destination for a diverse range of bird species, including thrushes, waxwings, wood warblers, finches, mockingbirds, pine siskins, goldfinches, sparrows, redpolls, crossbills, bluebirds, and chickadees. Its seeds and buds hold particular allure for these avian visitors, making Smooth Alder an essential feature in any bird-friendly habitat.

• Grows up to 10-20 ft. high (3-6 m) and 12-15 ft. wide (3-5 m).
• Performs best in full sun in moist to wet soils. Tolerates some shade, but full sun is best. Tolerates clay soils, poor soils, and seasonal flooding.
• Great choice along ponds and streams and other moist to wet areas of the landscape, including bog gardens, rain gardens, swamp borders, or wet meadows.
• No serious pest or disease issues. Keep an eye out for canker, powdery mildew, leaf curl, aphids, leaf miners, tent caterpillars, lace bugs, and flea beetles.
• Propagate by seed. Seeds could be planted immediately after harvest, but stratification improves germination.
• Native to eastern North America and can be found from western Nova Scotia and southern New Brunswick south to Florida and Texas.