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Woody > Alnus > Alnus incana > Alnus incana subsp. rugosa

Alnus incana

ssp. rugosa

Speckled Alder or Hazel Alder

Origin:  It is native to North America, including Canada and the northeastern United States from Hudson Bay to Newfoundland south to Michigan, Minnesota and into Virginia. Incana refers to the grey coloured leaf surfaces, while rugosa means sunken in reference to the furrowed leaf veins.
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An ordinary tree rarely seen in the cultivated landscape that is one of the first to flower in the spring.

Michael Pascoe, NDP., ODH., CLT., MSc. (Plant Conservation)


Tree (deciduous), Shrub (deciduous)
Alnus rugosa
USDA Hardiness Zone
2 - 6
Canadian Hardiness Zone
0a - 6a
RHS Hardiness Zone
H7 - H6
Temperature (°C)
(-45) - (-18)
Temperature (°F)
(-43) - 0
5-8 m
5-8 m
Description and Growing Information
Flowering Period
General Description
A fast growing tree, typically multi-trunked, wrinkled green-grey leaves with little to no autumn colour. This species has been placed on the IUCN Red List as least concern.
It has limited use in the landscape as it is not an ornamentally significant species. It does find use in land reclamation since its roots have the ability to fix nitrogen and thus it is tolerant of very poor soils. Its seed are consumed by a wide variety of birds species while some species of butterfly larvae are known to feed on the leaves thus it may be used to attract wildlife to the landscape.
Grow in acidic, moist soils.
ID Characteristic
Bark with pronounced lenticels presenting a speckled appearance, dull green wrinkled leaves with furrowed veins and red hairs on the underside.
Diseases can include canker, which can be severe, leaf curl and powdery mildew. Insect pests may include flea beetles, lace bugs, tent caterpillars, leaf miners and aphids. On alkaline soils chlorosis will occur.
Marshlands, coastland and riverbanks.
Bark/Stem Description
Often multi-stemmed with reddish-brown bark covered in grey, pronounced lenticels.
Leaf Description
The leaves are 5-10 cm long, with significantly wrinkled surfaces, dull green in colour, wedge-shaped at the base with an acute apex, doubly serrate margins and red hairs on the underside. There is no significant autumn colour.
Flower Description
Monoecious, catkins appearing in March to early April prior to leaf emergence. Male catkins are slender, cylindrical and drooping to 4-5 cm long, purplish-brown and covered with yellow pollen. The female catkins are green, rounded to 1.25 cm and are clustered on short stalks. Pollination is anemophilous.
Fruit Description
The strobiles (fruiting cones) are 1.5-2 cm long, short stalked or sessile and are composed of winged seeds (samara) 2-2.5 mm long. The strobile, which resemble small pine cones turn brown in autumn and persist into the winter months. Several species of bird feed on the seed from the strobiles.
Colour Description
Dull green leaves, red-brown bark with pronounced grey lenticels, brown cones and little or no autumn colour.
Texture Description
It is a coarse textured plant and remains that way throughout the year.
Natural stands occur primarily through suckering and or layering. Fresh seed may be sown in a sand based coldframe over the winter months with germination occurring in the spring. Greenhouse sown seed requires stratification of 60-90 days at 5°C.
Ethnobotanical Uses (Disclaimer)
It was used in the past by Indians to relieve anemia. When it is combined with powdered bumblebees it assists in the relief of pain during childbirth. Speckled alder tea was was used in the treatment of diarrhea and jaw pain as well as many other symptoms such as backaches, bruises, sore eyes and sprains.
Kershaw, L. (2001). Trees of Ontario, including tall shrubs. Edmonton: Lone Pine Pub. Mckenney, D. W., Pedlar, J. H., Lawrence, K., Campbell, K., & Hutchinson, M. F. (2007). Potential Impacts of Climate Change on the Distribution of North American Trees. BioScience, 57(11), 939.