Alnus alnobetula subsp. sinuata
Common name: 
Sitka Alder
Wavy Leaf Alder
AL-nus al-no-BET-u-la sin-u-AH-ta
Alnus viridis subsp. sinuata
Alnus sinuata
Native to (or naturalized in) Oregon: 
  • Deciduous, thicket forming shrub or small tree, often with several trunks, 20-35 ft (9-10 m) tall, taller at lower elevations.  Twigs glossy light brown to yellow-brown, at first pubescent and dotted with glands, later smooth with conspicuous lenticels, buds are sessile (i.e., without a stalk).  Bark is reddish-brown, gray or grayish-green, smooth, thin.  Leaves alternate, simple, 4-13 cm long, 4-7.5 cm wide, ovate to ovate-oval, thin, papery, doubly serrate to slightly lobed, green to yellowish-green above, paler and smooth below.
  • Sun part shade.  A pioneer species, and is adapted to soils that are too poor for growth of other trees, but best on moist sites.  Its ability to fix nitrogen allows it to invade soils with low fertility, such as those recently exposed by glaciers or avalanches.
  • Hardy to USDA Zone 2         Native to a large area, from the Yukon and western and southern Alaska southward to northern California and eastward to southwestern Alberta and western Montana, also northeastern Oregon.  Usually found above 3,000 ft (900 m) elevation, although it also grows in the snowy coastal tundra of Alaska.   Sometimes called "slide alders", since they form almost impenetrable thickets in avalanche swaths in the Cascades.
  • 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 of the North Americac subspecies of Alnus alnobetula are (1) A. alnobetula supsp. crispa - (American) Green Alder and (2) A. alnobetula subsp. sinuata - Sitka Alder. 
  • viridis: green; sinuata: strongly wavy margin,; crispa: finely waved, closely curled
  • Oregon State Univ. campus: south of Peavy Hall, native plants area.


Click image to enlarge
  • female and male catkins

    female and male catkins

  • plant habit, summer

    plant habit, summer

  • leafy shoot

    leafy shoot

  • leaf and buds

    leaf and buds

  • leaf margin, surface

    leaf margin, surface

  • leaves, cones and catkins

    leaves, cones and catkins

  • stem