Sitka alder

Silhouette - Sitka alder
  • Latin name: Alnus viridis ssp. sinuata (Regel) A. Löve et D. Löve
  • French name: Aulne de Sitka
  • Taxonomic Serial Number: 181895
    19476 [syn. A. sinuata (Regel) Rydb.]
Description

Leaves

  • Leaf with detail of double-toothed margin - Sitka alder

Form

  • Broadly oval, thin
  • Resinous and fragrant when young
  • Mostly hairless
  • Base broad, often asymmetrical
  • 6–8 veins per side
  • Veinlets irregularly branched

Length

  • 7–15 cm

Colour

  • Shiny, deep yellowish-green

Margin

  • Teeth sharp, gland-tipped, of 2 sizes, none near the petiole
  • Each vein ends in a large tooth

Buds

  • Lateral bud and leaf scar - Sitka alder
  • Lateral bud and leaf scar - Sitka alder

Form

  • Curved, sharp-pointed, stalkless
  • 3–5 overlapping scales
  • Usually arranged in 2 ranks along the twig
  • Leaf scars raised, crowded along the twig

Length

  • 12–14 mm

Colour

  • Purplish-brown

Twigs

  • Winter twig - Sitka alder

Form

  • Slender, sticky when young
  • Dwarf shoots may develop

Colour

  • Light reddish-brown or yellowish-brown with pale lenticels

Flowers

  • Mature seed catkin - Sitka alder
  • Pollen catkin in winter condition - Sitka alder

Form

  • Pollen catkins stalkless, in pairs
  • Seed catkins enclosed in a bud in winter

Length

  • About 1 cm in winter, 10–14 cm at pollination

Timing

  • Open with the leaves

Stucture

  • Monoecious

Fruits

  • Fruit scale (left); nutlet (right) - Sitka alder

Form

  • Several mature seed catkins in an erect cluster

Length

  • 12–20 mm with equally long stalks

Width

  • Nutlet about the same width as wings

Bark

Form

  • Smooth with long horizontal lenticels

Colour

  • Reddish- to greyish-brown

Size

Height

  • To 15 m

Diameter

  • To 20 cm

Tree form

  • Silhouette - Sitka alder

Forest-grown

Trunk

  • Slender

Crown

  • Open, with short horizontal branches

Root system

  • Shallow

Habitat

Site

  • Cool moist sites in the mountains
  • Often where landslides have created openings

Range

From the Pacific Coast to the western slopes of the Rocky Mountains

Insects and diseases

Insects and diseases that are found most frequently and/or that cause the most damage in our Canadian forests.

Photos
  • Sitka alder
Distribution map
Distribution map - Sitka alder
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