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Trees of Iowa: An Interactive Key

Douglas-Fir
(Pseudotsuga menziesii)



The Douglas fir is native to the western mountain states. It has been planted widely in Iowa for ornamental and windbreak use.

Hardiness: zones 5 through 6

Growth Rate: medium

Mature Shape: pyramidal mature shape

Height: 40 to 60 feet

Width: 15 to 25 feet

Site Requirements: None.

Flowering Dates: March - June

Seed Dispersal Dates: September - March

Seed Bearing Age: 7-10 Years

Seed Bearing Frequency: Every 2-11 Years

Seed Stratification: Prechill 21 days at 34F to 40F

Douglas Fir Fruit Douglas Fir Fruit

The tree has dense and compact foliage, holds its branches well to theground.  It grows 40 to 60 feet high.

Douglas Fir FruitDouglas Fir Fruit

The needles are soft, flattened, slightly pointed, 1 to 1-1/2inches long and grow around the branch to give it a full, rounded appearance.  They are grooved on the upper surface, and have a white band on each side of a prominent midrib beneath.

Douglas Fir FruitDouglas Fir Leaves

The twigs are fine and the buds are long, pointed, dark orange-red in color and shiny.  They are sometimes termed "cigar-shaped."
 
The cones of the Douglas fir are distinct, 1-1/2 to 4 inches long.  Protruding from beneath the thin rounded scales is a conspicuous, three-pointed bract.

On older trees the reddish brown bark is broken into oblong, longitudinal plates and may be 10 to 12 inches thick.  On young and smaller trees, the bark is thin, ashy gray and may have resin blisters.

 

Click on a thumbnail image below to view a larger picture.
Duoglas Fir Fruit Douglas Fir Fruit Douglas Fir Fruit Douglas Fir Fruit Douglas Fir Fruit Douglas Fir Leaves Douglas Fir Twigs Douglas Fir Form