SelecTree: Tree Detail
Photo Locations: BioPark Botanic Garden - Albuquerque, NM, UC Berkeley Botanic Garden - Berkeley, CA, Los Angeles County Arboretum - Arcadia, CA and Regional Parks Botanic Garden, Tilden Regional Park - Berkeley, CA
Utility friendly tree.
Extremely hardy to cold. Native Americans used the bark as a laxative. The leaves have gray undersides. Often found near water and in dense thickets. Not widely available in nurseries.
Native to North America and Eurasia.
Additional Common Names
GRAY ALDER, THINLEAF ALDER, MOUNTAIN ALDER, RIVER ALDER
Erect or Spreading with a Low Canopy.
Has Deciduous foliage.
Height: 20 - 25 feet.
Width: 15 - 20 feet.
Growth Rate: 24 to 36 Inches per Year.
Longevity 40 to 150 years.
Leaves Ovate, Medium to Dark Green, Bronze or No Change, Deciduous.
Flowers Inconspicuous. Green, Red or Yellow. Flowers in Spring. Has separate male and female flowers on the same tree (monoecious).
Prolific, Yellow or Brown Cone, Medium (0.50 - 1.50 inches), fruiting in Spring or Summer.
Bark Dark Gray or Red Brown, Smooth.
Shading Capacity Rated as Dense in Leaf.
Shading Capacity Rated as Moderately Dense out of Leaf.
Litter Issue is Dry Fruit.
Tree Site Conditions & Constraints
Sunset Zones 2, 3, 7 and 10.
USDA Hardiness Zones 2 - 6.
Exposure Full Sun to Partial Shade.
Wet to Moist Soil.
Loam or Sand Texture.
Highly Acidic to Neutral Soil pH.
Seaside Tolerance is Not Suited.
Pests & Disease Information
Susceptible to Armillaria and Root Rot.
Health, Safety & Environmental Concerns
Root Damage Potential Rated as Moderate.
Allergy Health Hazard.
Desirable Wildlife Plant.
Special Uses & Values
Riparian or Screen.
Cite this tree:
SelecTree. "Alnus incana Tree Record." 1995-2018. Jun 21, 2018.
< https://selectree.calpoly.edu/tree-detail/alnus-incana >