Douglas-fir (Pseudotsuga menziesii var. menziesii - left) and Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca - right).
"…a species of fir… " [Lewis', 6 February 1806.]
Douglas fir is one of western North America's larger trees and certainly among its most important economically. It is a co-dominant in the "old growth forests" of the Pacific Northwest and common in the Rocky Mountains. Archibald Menzies (1754-1842), the naturalist on a around-the-world voyage captained by George Vancouver (1757-1798), was the first to collect the tree in July of 1792. Lewis wrote a detailed description of it on 6 February 1806, having observed the tree since entering the Rocky Mountains in Montana months before. What was to follow can only be described as a nomenclatural nightmare.
In 1803, the English expert on conifers, Aylmer Bourke Lambert who would late sponsor Pursh's writing of an 1813 flora wherein many of Lewis and Clark's new species would be described, named Menzies' tree Pinus taxifolia. He did not realize this name had already been used for an European species. Two years later, the French botanist and clergyman Jean Louis Marie Poiret attempted to correct the error by given the tree another name, but remarkably, his name too was proposed previously. According to the rule of botanical nomenclature, both names were incorrect, and another was required. Pursh in 1813 apparently recognized he had two expression of the species as he wrote: "I have among my specimens two varieties, or probably distinct species, which for want of fructification [cones] I cannot decide: one has acute leaves, green on both sides; the other emarginate leaves, glaucous underneath." He had the 1792 Menzies specimen, and apparently a now lost Lewis and Clark collection, probably from Idaho or Montana. Indeed, the mountain phase is now known as Pseudotsuga menziesii var. glauca.
Pseudotsuga menziesii var. menziesii is the tall, mainly coastal tree that ranges from British Columbia to California. It was this plant that Menzies found and Lewis described. In spite of its huge size and potential value, the tree remained largely unknown until collected again by the Scottish naturalist David Douglas in 1825. Douglas was in the Pacific Northwest collecting plants for the Royal Horticultural Society. It was Douglas who introduced the tree into cultivation, and it is his trees that are seen frequently in gardens and around estates in Europe today.
In 1832 Constantin Samuel Rafinesque-Schmaltz described six species of "fir" from the Pacific Northwest. All of his new species were based not on specimens, but upon Lewis' descriptions of the trees written over a period of a few days in February of 1806. Just a few weeks prior to the formal publication of Rafinesque's Abies mucronata, English botanist and librarian David Don proposed Pinus douglasii. In 1867, it was realized that Douglas-fir, as the tree was now called, was neither a pine nor a fir but something else entirely, and the French horticulturist Elie-Abel Carrière proposed Pseudotsuga for the tree. For more than twenty years, the tree was known as Pseudotsuga douglasii only to be altered in 1889 to Pseudotsuga taxifolia. In 1897, even Pseudotsuga mucronata was proposed. For the next half century botanists argued over which name was correct. Finally, in 1950, a Spanish botanist Joäo Manuel Antonio do Amaral Franco discovered an obscure 1825 journal where a French botanist, Charles Mirbel proposed Abies menziesii as a new name for the incorrect Pinus taxifolia suggested by Lambert in 1803. Thus, in 1950, the name of Douglas-fir was settle and it became Pseudotsuga menziesii.
It is fitting that this magnificent tree should be so closely tied to three of the early naturalists in the Pacific Northwest, Archibald Menzies, Meriwether Lewis and David Douglas. The coastal variety can reach heights close to 90 meters, but the montane express rarely exceeds more than 50 meters. Both are common and may be easily identified by the unique bracts found on each scale of the cone.
