|Western Hemlock – Tsuga heterophylla|
In 1947, RCW 1.20.020 of the Washington state legislature declared, “that certain evergreen tree known and described as the Western hemlock (Tsuga heterophylla) is hereby designated as the official tree of the state of Washington.” What do we have to say about “that certain evergreen tree?” For starters, the Western hemlock is a cone-bearing (coniferous) tree that comprises a significant portion of old-growth forests in the Pacific Northwest. The cones are generally no longer than one inch, much shorter than other species here at SHADOW Lake Nature Preserve, with the only exception of the Western red cedar. The needle-like leaves of the Western hemlock are short, broadly flat, and of course evergreen. Evergreen plants are those that bear leaves persisting for multiple growing seasons as opposed to deciduous trees, which drop their leaves annually. Examples of local evergreen species are pine, spruce, cedar, juniper, fir, larch, and hemlock trees. The Western hemlock is a shade-loving species that disproportionately influences the old-growth forest community relative to its abundance. This feat is accomplished by shading the understory with its dense spreading canopy, which incidentally happens to create the ideal conditions for other hemlock trees to thrive. If a tree falls in the woods, the race is on to exploit the newly available site and monopolize that sweet sunlight. Nurse logs are fallen trees that provide advantageous positioning for germinating seeds, and Western hemlocks seedlings are commonly seen growing in rows along such fallen logs. Another trick Western hemlocks have is to grow in very close proximity to Douglas fir trees, using the sloughed bark of the latter as a substrate for germinating. As the hemlock continues to grow, hugging its neighbor’s trunk, it is referred to as a minion of the Douglas fir.