Alnus incana ssp. rugosa
Speckled Alder
Other Common Names: Smooth Alder, Hazel Alder

Previously known as:  Alnus rugosa
 Genus:
 Plant Type:
 Growth Forms:
 Hardiness:
 Flower Notes:
Flowers are monoecious, appearing in catkins in March-early April before the leaves emerge.
 Foliage Notes:
Dull green leaves with wrinkled surfaces and red-hairy undersides are wedge-shaped at the base and pointed at the tip with doubly serrate margins.
 Stem Notes:
White warty lenticils speckle the bark.
 Fruit Notes:
Female catkins are followed by 1-inch long fruiting cones composed of winged seeds. These fruiting cones persist into winter, resemble small pine cones, and are attractive to birds.
 Ultimate Height:
15-25' feet
 Ultimate Spread:
15-25' feet
 Bloom Times:
 Light Requirements:
 Soil Water Requirements:
 Soil Notes:
Best grown in medium to wet soils. Tolerates mucky soils.
 Range:
Native to Canada and northeastern United States.
 Maintenance:
 Ecological Functions:

The Purdue Arboretum is a collaboration between the Department of Horticulture and Landscape Architecture and Administrative Operations

Purdue Arboretum, 625 Agriculture Mall Dr, West Lafayette, IN, 47907
© 2026 Purdue UniversityAn equal access/equal opportunity universityCopyright ComplaintsMaintained by Purdue Arboretum Explorer
Contact Purdue Arboretum at arboretum@purdue.edu for accessibility issues with this page | Accessibility Resources | Contact Us