Red alder

Silhouette - red alder
  • Latin name: Alnus rubra Bong.
  • French name: Aulne rouge
  • Synonym(s): Western alder , Oregon alder
  • Taxonomic Serial Number: 19474
    183515 [syn. A. oregona Nutt.]
Description

Leaves

  • Leaf with details of double-toothed margin (above) and hairy veins on lower surface (below) - red alder

Form

  • Oval to rhombic, tapered from the middle to both ends
  • Thick, not sticky
  • Veins hairy on lower surface
  • 8–15 veins per side, impressed on upper surface
  • Veinlets forming a ladder-like pattern
  • Considerable leaf-fall during summer

Length

  • 7–13 cm

Colour

  • Upper surface dull dark green
  • Lower surface greyish

Margin

  • Double-toothed, the largest teeth almost lobe-sized
  • Margin clearly rolled under

Buds

  • Lateral bud and leaf scar - red alder

Form

  • 2 or 3 hairy scales that meet along their edges
  • Leaf scars with 3–5 vein scars

Colour

  • Green

Twigs

  • Winter twig - red alder

Form

  • Moderately stout
  • Triangular or round in cross-section
  • Pith indistinctly triangular in cross-section

Colour

  • Purplish-brown

Flowers

  • Mature seed catkin after nutlets shed - red alder
  • Pollen catkin in winter condition - red alder

Form

  • Pollen catkins in small clusters at the shoot tips
  • Seed catkins visible in winter in small lateral clusters

Length

  • Pollen catkins about 3 cm in winter, 10–15 cm at pollination
  • Seed catkins about 5 mm

Structure

  • Monoecious

Fruits

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

Form

  • Mature seed catkins short-stalked, abundant
  • Nutlet narrow-winged or encircled by wing

Length

  • Mature seed catkins 15–25 mm
  • Nutlet about 2 mm

Timing

  • Ripen in early autumn, shed in late autumn and into winter

Bark

Form

  • Smooth, occasionally shallowly furrowed, with age separates into irregular flat plates

Colour

  • Light grey, usually almost white with lichens
  • Wounds turn red

Wood

Texture

  • Fine, even-textured

Colour

  • Light brown, often turns reddish after cutting

Uses

  • Wood carving, furniture, firewood

Size

Height

  • To 25 m

Diameter

  • To 60 cm

Maximum age

  • 75 years

Tree form

  • Silhouette - red alder

Forest-grown

Trunk

  • Straight, slightly tapered
  • Distinct to top of the crown

Crown

  • Narrow, rounded

Open-grown

Crown

  • Extends to the ground
  • Broadly conical

Root system

  • Shallow, wide-spreading

Habitat

Site

  • Floodplains and along streams

Light tolerance

  • Intolerant of shade

Associated species

  • In pure stands; also mixed with black cottonwood, grand fir, Douglas-fir, western redcedar, western hemlock, western yew, bigleaf maple, and vine maple

Range

In Canada, a narrow band within 150 km of the Pacific coast; in the United States, the states of Washington and Oregon

Insects and diseases

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

Photos
  • Red alder
  • Red alder
  • Red alder
Distribution map
Distribution map - red alder
Date modified: