Tsuga heterophylla is a cone-bearing (coniferous) tree. It is one of two species of hemlock trees that are found primarily along the coast of British Columbia (Pojar & MacKinnon 1994).
Description:
T. heterophylla can grow up to 60 m tall. The top of the tree typically bends downwards, giving it a nodding appearance. The branches are covered with short, flat needles that are of unequal length and irregularly arranged around the stem. The pollen cones that form among the needles are small (3-4 mm) and inconspicuous, while the female seed cones found on the tips of the branches are larger (~2 cm long) and persist for 2 years on the tree. The bark of mature trees is rough with grooves. The oldest T. heterophylla have been reported to be as old as 500 years (Klinkenberg 2017; Pojar & MacKinnon 1994; US Forest Service n.d.).
Ecology:
Western hemlock can be found from sea level to mid elevations of the British Columbia coast. It is also found in the wet region of the Kootenays west of the Rocky Mountains (MFLNRO n.d.). This species is tolerant of dry sites but is more abundant in temperate wet locations. Western hemlock tolerates shade and the seeds can become established in the organically rich understory of other coniferous trees, such as Douglas fir (Pojar & MacKinnon 1994). Young western hemlock trees can often be seen growing on top of decomposing stumps or nurse logs (Klinkenberg 2017; US Forest Service n.d.).
Young western hemlock trees are an important food for deer and elk. The native peoples of the coast have used the bark for dying and the wood for carving into useful cooking tools. The tender shoots and inner bark have been used as food, while the pitch (resin that seeps out of wounds in tree trunks) has been used for medicinal purposes (Packee 1990; Pojar & MacKinnon 1994).
Young western hemlock trees are an important food for deer and elk. The native peoples of the coast have used the bark for dying and the wood for carving into useful cooking tools. The tender shoots and inner bark have been used as food, while the pitch (resin that seeps out of wounds in tree trunks) has been used for medicinal purposes (Packee 1990; Pojar & MacKinnon 1994).
Reproduction and Dispersal:
When the western hemlock trees reach 25 to 30 years of age, they begin to produce seed cones. The female seed cones are initially green in the spring when they are receptive to pollen. Following pollination, the cone scales close and gradually turn brown. In late October, the cone scales open in response to dry weather; the seeds are then released and carried by the wind (Packee 1990).
References cited:
Klinkenberg B, editor. 2017. E-Flora BC: Electronic Atlas of the plants of British Columbia [eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [accessed 2018 Jan 29]. http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Tsuga%20heterophylla.
[MFLNRO] Ministry of Forests, Lands and Natural Resource Operations. n.d. Tree species compendium --Douglas fir. [accessed 2017 Jan 31]. https://www.for.gov.bc.ca/hfp/silviculture/compendium/DouglasFir.htm.
Packee EC. 1990. Tsuga heterophylla (Raf.) Sarg. Western hemlock. In: Burns RM, Honkala BH, tech. cords. 1990. Silvics of North America: 1. Conifers. Agriculture Handbook 654. US Department of Agriculture, Forest Service, Washington, DC. [accessed 2018 Jan 29]. https://www.srs.fs.usda.gov/pubs/misc/ag_654_vol1.pdf.
Pojar J, MacKinnon A. 1994. Plants of coastal British Columbia: including Washington, Oregon & Alaska.
Vancouver: Lone Pine Publishing.
US Forest Service. n.d. Pacific Northwest old growth forest – Western hemlock (Tsuga heterophylla). [accessed 2018 Jan 29]. https://www.fs.fed.us/pnw/owl/oldgrowth/tree/western_hemlock.htm.
[MFLNRO] Ministry of Forests, Lands and Natural Resource Operations. n.d. Tree species compendium --Douglas fir. [accessed 2017 Jan 31]. https://www.for.gov.bc.ca/hfp/silviculture/compendium/DouglasFir.htm.
Packee EC. 1990. Tsuga heterophylla (Raf.) Sarg. Western hemlock. In: Burns RM, Honkala BH, tech. cords. 1990. Silvics of North America: 1. Conifers. Agriculture Handbook 654. US Department of Agriculture, Forest Service, Washington, DC. [accessed 2018 Jan 29]. https://www.srs.fs.usda.gov/pubs/misc/ag_654_vol1.pdf.
Pojar J, MacKinnon A. 1994. Plants of coastal British Columbia: including Washington, Oregon & Alaska.
Vancouver: Lone Pine Publishing.
US Forest Service. n.d. Pacific Northwest old growth forest – Western hemlock (Tsuga heterophylla). [accessed 2018 Jan 29]. https://www.fs.fed.us/pnw/owl/oldgrowth/tree/western_hemlock.htm.