This is a blog about the native conifers of the Pacific Northwest. It is a companion to the Northwest Conifers site. The blog will focus on timely and interesting details about our conifers, their connections to the rest of the environment, and our connection to them.

Thursday, May 21, 2020

Focus on Hemlocks

Hemlock trees are not the source of the poison hemlock that killed Socrates. They are not poisonous and not even related to poison hemlock, but the foliage looks similar, and crushed needles have a similar smell. This, no doubt, led European settlers of North America to call these trees hemlocks. The scientific name of the hemlock genus is Tsuga, which also has a curious origin. Rather than the usual Latin name, Tsuga is the Japanese name for Japanese hemlock. In the nineteenth century, hemlocks were first classified as a pine, then as a fir, and later as a spruce. After the discovery of Japanese hemlock, hemlocks were assigned to the genus Tsuga.

Hemlocks are in the pine family (scientific name: Pinaceae) and are unique in the family. They have a distinctive drooping leader at the top of the tree. Hemlocks also have the smallest cones in the pine family. They can tolerate growing in the shade of other large trees for years. However, hemlocks can grow to enormous size and eventually dominate other trees in the forest. Although they can grow in the shade of Douglas fir for hundreds of years, in the normal succession of a Douglas fir forest, the hemlocks will eventually prevail, forming the canopy of the mature forest.

Western hemlock
At least nine species of hemlock grow in North America and Asia. Curiously, they are absent from Europe. Four species are native to North America, with two of them in the Pacific Northwest, western hemlock and mountain hemlock. They are important commercial trees, used to make lumber, plywood and pulp for paper. However, the beauty of their drooping form and delicate branchlets far exceeds their usefulness as lumber. And pulp? How degrading. Their purpose is better served by horticulturists, who have developed many popular cultivars.

Mountain hemlock
Hemlock needles are short and usually flattened on the twig, but they have a tendency to deviate from their flattened position. The needles are dark on top with two white lines on the lower surface. The cones are usually less than an inch long, and the scales are thin and rounded. Mountain hemlock is an exception to these characteristics, with bluish needles that make no pretense about lying flat, surrounding the twig in all directions. Also, the cones are over achievers, being twice as large as other hemlock cones.

Western hemlock at Elk Mountain
Hemlocks flourish in wet, cool environments. They can tolerate a heavy snowpack, not with strength, but by bending. They will spring back when the snow melts in the spring. On the other hand, one thing they do not tolerate is drought. Unless you live east of the Cascade Mountains, a hemlock would be a graceful addition to your yard, whether it is a cultivar or one of our natives.

More info
Tsuga at conifers.org
Tsuga in Wikipedia

8 comments:

  1. I love the "ice cream" trees. it was one of the first trees I learned to spot at camp Adams Outdoor School. Have you read the book "The Wild Trees" by Richard Preston? There is a section that discusses OSU and the early work in canopy studies for big temperate rainforest trees.

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    1. I've read about the canopy studies, but haven't read this book. I'll check it out. Thanks.

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  2. You might also enjoy this: https://www.gentleartofwandering.com/looking-for-medallion-trees-on-the-faulty-trail/ I haven't seen many of these trees, but once I get a friend who likes to walk at a gentle pace, I'll find these trees myself.

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  3. Interesting blog. What interests me is that the medallions tell the age of the tree. Also love the photos of ponderosa bark.

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  4. I enjoyed reading your lastest post, Ken. Interesting addition to your informative blog. I always learn something new about conifers on your website, thank you.

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    1. Thanks. Stay tuned for a post on Mt. Hemlock.

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  5. Nice... I did not realize the hemlocks would outlast the firs in a forest. Assuming the firs were not cut down of course... :-0

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    1. Also assuming the hemlocks were not cut down. Ditto for being burned up.

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