Rocky Mountain Douglas-fir

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)

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

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

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