Home › Pinaceae › Pseudotsuga › Pseudotsuga menziesii (Douglas-fir)

menziesii – refers to Scottish naval surgeon and botanist Achibald Menzies (1754-1842), who explored the PNW with Capt. George Vancouver

Native range: British Columbia to California, Rocky Mountains

Pseudotsuga menziesii GPNF

Leaves:

  • needles
  • spirally arranged, ~2 ranked on shaded branches
  • needles ~1” (2-3 cm) long
  • short petiole
  • upper – grooved
  • lower – 2 white stomatal bands
  • slender, petiole-like stalk which sits upon a short, oblique leaf cushion
  • point bud tips, reddish orange & shiny, bud scales stick to leaves later in season

Pseudotsuga menziesii branch underside 2

Cones:

  • monoecious
  • female cones:
    • three-forked exserted bract (“back legs and tail of a mouse hiding in the cone”)
    • 5-10 cm long
    • in mature trees, located near the upper crown
  • pollen cones:
    • small
    • reddish-brown

Pseudotsuga menziesii cone Port Townsend

Pseudotsuga menziesii pollen cones Squak Mountain WA

Other characteristics:

  • tree up to 300 ft.
  • evergreen
  • irregularly whorled branches
  • ovate leaf scars on branches
  • prefers sun
  • leaves can vary in length and width between trees
  • genetically diverse
  • bark deeply furrowed & reddish brown when mature
  • drooping branches
  • erect leader

Douglas Firs Mount Hood National Forest

Relevant info:

  • yields more timber than any other tree in North America
  • straight trunks are made into telephone poles and used for ship masts
  • Oregon’s state tree

Ecology & Adaptations:

  • British Columbia to California, east to Alberta and Colorado
  • found in moist to dry areas from sea level to mid- elevations in the mountains
  • fire resistance – on mature trees, very thick (4-12”), corky bark, which enables trees to survive moderate surface fires
  • pollination by wind
  • seed dispersal:
    • seeds have a relatively large, single wing and are primarily dispersed by wind and gravity
    • when trees destroyed by fire, seeds arrive via the wind
    • stand-destroying disturbance (wildfire, logging, extensive wind-throw) initiates a new cohort of seedlings birds and small mammals also aid dispersal
  • not tolerant of shade - as tree matures, it sheds lower, shaded branches and concentrates needle production on upper branches exposed to direct sunlight
  • succession:
    • first conifer to establish on drier sites
    • very long-lived species, so 1,000 years may pass before a shade-tolerant species overcomes this pioneer
  • herbivore defense – chemical compounds, such as tannins and terpines, in leaves
  • wildlife:
    • seeds are important food sources for small mammals (voles, chipmunks) and songbirds (sparrows, finches)
    • Douglas squirrels also eat pollen cones, inner bark, and young needles