Rocky Mountain Douglas-fir

Silhouette - Rocky Mountain Douglas-fir
  • Latin name: Pseudotsuga menziesii var. glauca (Beissn.) Franco
  • French name: Douglas bleu
  • Synonym(s): Interior Douglas-fir , blue Douglas-fir
  • Taxonomic Serial Number: 183428
  • NA5 , 3b
Description

Leaves

Form

  • Needles evergreen
  • Remaining on tree for 5–8 years
  • Often not parted on the upper side
  • Flat, flexible, grooved above
  • Often sharp-pointed
  • Narrowed at the base into a slender short stalk, set on a leaf-cushion
  • Needles spirally arranged along the twig
  • On horizontal branches, spreading out from the sides in 2 ranks, or spreading out from 3 sides
  • Midvein prominent
  • 2 resin ducts visible in cross section
  • Strong odour when crushed

Colour

  • Distinctly bluish-green

Buds

Form

  • Terminal bud narrowly conical, sharp-pointed
  • A small cluster of lateral buds occurs just below the terminal bud, separated by a few needles
  • Other lateral buds scattered along the twig

Length

  • Terminal bud to 10 mm

Colour

  • Many shiny reddish-brown overlapping scales

Twigs

Form

  • Moderately stout and flexible, hairy
  • A low ridge of bark darkened at the forward end forms a leaf-cushion
  • After the needles have fallen, the branchlets show slightly raised oval scars on the leaf-cushions

Colour

  • Greenish-brown becoming greyish-brown

Seed cones (immature)

Form

  • Conelets borne in the upper part of the crown, in leaf axils near the forward end of previous year’s twig
  • Seed-cone buds are larger than the shoot buds

Length

  • About 30 mm

Colour

  • Green to purple to red

Structure

  • At pollination, oblong
  • Erect, short-stalked, with distinctive 3-pronged bracts extending beyond the scales and partially obscuring them
  • After pollination, the cone stalk bends downward

Timing

  • Mature in late summer of 1st season

Pollen cones

Form

  • Cylindrical to conical, fleshy, catkin-like
  • Pendulous
  • Pollen-cone buds paler than the shoot buds

Length

  • 10–20 mm

Colour

  • Yellow to orange-red

Structure

  • Borne in the upper-middle, middle, and lower parts of the crown, in leaf axils of previous year’s twigs

Timing

  • Pollination takes place in early spring as new leafy shoots start to elongate; cones then wither and fall away

Seed cones (mature)

  • Seed cone with reflexed bracts - Rocky Mountain Douglas-fir

Form

  • Narrowly ovoid
  • Pendulous on stout stalks

Length

  • Less than 8 cm

Colour

  • Yellowish-brown to purplish-brown

Structure

  • Scales numerous, broad, rounded, leathery
  • Bracts prominent, 3-pronged, usually bent back, longer than the scales

Timing

  • Seeds shed throughout fall, winter, and spring
  • Cones drop intact after seed dispersal

Seeds

  • Cone scale outer surface with bract (left), inner surface with winged seed (right) - Rocky Mountain Douglas-fir

Form

  • Somewhat triangular

Length

  • Seed 5–7 mm
  • Seed wing 15–18 mm

Colour

  • Shiny reddish brown

Seedlings

Form

  • Newly germinated seedlings with a stalk surmounted by a whorl of 5–10 upcurved cotyledons with smooth edges
  • Needles form above the cotyledons, clustered at first, later spreading along the new shoot

Length

  • Seedlings about 4 cm
  • Cotyledons about 2 cm

Colour

  • Cotyledons green

Bark

Form

  • Smooth, thin, resin-blistered when young
  • Becoming deeply furrowed with irregular, broad ridges
  • Up to 30 cm thick

Colour

  • Grey when young, becoming dark reddish-brown

Wood

Texture

  • Moderately heavy and hard
  • Exceptionally strong

Colour

  • Heartwood reddish-brown
  • Sapwood yellowish-white

Morphology

  • Marked contrast between earlywood and latewood
  • Resin ducts present

Size

Height

  • To 40 m

Diameter

  • To 100 cm

Maximum age

  • 300 years

Tree form

  • Silhouette - Rocky Mountain Douglas-fir

Trunk

  • Tapered, long, limby

Crown

  • Principal branches more ascending than coastal variety

Habitat

Site

  • Thrives in mountains, under colder and drier conditions than the coastal variety

Light tolerance

  • Requires some shade in 1st year but then thrives in sunlight

Associated species

  • In pure stands or as a dominant component of mixed stands with ponderosa pine, lodgepole pine, western redcedar, western larch, and western white pine

Range

Southern British Columbia, southward into the United States and Mexico

Insects and diseases

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

Photos
  • Rocky Mountain Douglas-fir
  • Rocky Mountain Douglas-fir
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