Alnus alnobetula subsp. crispa
Common name: 
American Green Alder
Mountain Alder
Green Alder
AL-nus al-no-BET-u-la KRIS-pa
Alnus viridis crispa
Native to (or naturalized in) Oregon: 
  • Broadleaf, deciduous, large spreading shrub, 3-13 ft (1-4 m) tall.  Twigs smooth, dark brownish red, with many light lenticels (appear as dots). Leaves alternate, simple, ovate or broadly elliptic,  about 4-9 cm long and 2.5-5 cm wide, thick, apex short-pointed, base rounded or broadly wedge-shaped, margin sharply and finely toothed, sometimes undulated, shiny yellow green upper surface, pale green and with tuft of whitish hairs in vein angles.   Male flower catkins 2-7.5 cm long and female clusters only 6-10 mm long.  Fruit, cone-like, 10-15 mm long , yellow then brown, with a slender stalk.

  • Sun to shade, best in moist soil

  • Hardy to USDA Zone 1      Native distribution from Canada’s Northwest Territory and its Arctic Archipelago (Nunavut), south to Alberta and across Canada to the Maritime Provinces.  In the US it is found in Minnesota and east through the northern tier of states and south to Pennsylvania; populations are also found in Tennessee and Virginia.

  • Taxonomy: The Latin name Alnus viridis (Chaix) DC (1785) has long been attributed to green and Sitka alders; however, a closer look at the literature reveals that the name Alnus alnobetula  (Ehrh.) K. Koch has priority, since the latter name was published two years earlier, in 1783  (Chery, J., PhytoKeys 2015; (56): 1–6).  Hence the specific epithet alnobetula takes precedence over viridis.
  • Studies have shown that both Sitka Alder and Green Alder are part of a large circumpolar alder group (known as Alnus alnobetula) which is distributed across North America, Europe, and Asia.  Two North American subspecies of Alnus alnobetula are (1) A. alnobetula subsp. crispa - (American) Green Alder and (2) A. alnobetula subsp. sinuata - Sitka Alder.
  • ​ Note:  The common name, Mountain Alder, is applied to Alnus alnobetula supsp. crispa and Alnus incana subsp. tenuilolia
  •   viridis: green,  crispa: curled
Click image to enlarge
  • plant habit

    plant habit

  • leaves and fruit (cones)

    leaves and fruit (cones)

  • leafy shoot

    leafy shoot

  • leaf


  • leaves and developing and mature cones

    leaves and developing and mature cones

  • branch