Pseudotsuga description

Closeup of the underside of a sun foliage shoot of P. menziesii, showing pollen cone buds and the manner of leaf attachment to the twig [C.J. Earle].

Pseudotsuga Carrière 1867

Common Names

Douglas-fir (1).

Taxonomic notes

Description

Evergreen trees. Bark initially smooth with transverse resin blisters, with age becoming reddish brown, thick and corky, deeply fissured into scaly ridges or flaking. Branches often pendulous, irregularly whorled; epicormic branching common on late successional trees. Short (spur) shoots absent; leaf scars transversely elliptic, slightly raised proximally but essentially flush with twig distally (see figure at left). Buds elongate, not or slightly resinous, apex acute. Leaves borne singly, persisting 6-8 years, alternate, short-stalked, linear, flat, green and grooved above, with 2 white stomatal bands each containing 5-8 lines of stomata beneath; 2 marginal resin ducts and 1 vascular bundle. Cones borne on year-old twigs. Pollen cones axillary, cylindric. Seed cones maturing first season, terminal on short branchlets, consisting of numerous spirally arranged scales, each scale 2-ovuled. Mature cones shed whole, deflexed or pendent from a 2-10 mm long peduncle, ellipsoid, ovoid, or cylindric, lacking apophysis and umbo; scales persistent, apex rounded; bracts ± exserted, apex 3-lobed with the middle lobe long and narrow. Seeds winged; cotyledons 2-12. x=12, 13 (1, 2, and pers. obs.).

Range

Canada, USA, Mexico, Japan and China.

Big Tree

See P. menziesii var. menziesii.

Oldest

See P. menziesii var. menziesii.

Dendrochronology

There has been a great deal of work done with P. menziesii and a much smaller amount with P. macrocarpa. Have not looked into the literature on the Asian species.

Ethnobotany

Observations

P. menziesii is one of commonest trees in western North America, a serious weed in New Zealand, and easily found in most of the rest of the world's temperate terrestrial climate zones. The other species are of relatively limited occurrence and are seldom used as ornamentals.

Remarks

The genus name is derived from the Greek pseudo, false, and the Japanese TSUGA, hemlock (1).

Citations

(1) Lipscomb, Barney at the Flora of North America web site.
(2) Li 1975.