Tsuga canadensis - The Eastern Hemlock
Hello Everyone, today's plant profile should be familiar to you, I talk about Eastern Hemlock frequently on this blog and it's time I made a post that reflects my admiration.
To start let's deconstruct a common misnomer: While the name Hemlock connects back to the plant Poison Hemlock, Eastern Hemlock is not poisonous, English Settlers felt the scent of the foliage resembled that of the notorious herb. The Latin name Tsuga connects back to Japanese name for Hemlock Trees.
Now the basics: Eastern Hemlock is usually found in mountainous moist (but well drained) regions specifically around coves, canyons, ravines, and streams. The Tsuga family itself are a collection of evergreen conifers with an uncanny ability to grow on extreme slopes. The trunks themselves occasionally protrude from bare rock in bent forms (Image 4 from Kaaterskill falls, NY). Mature trees have pendulous flexible branches to avoid heavy snow loads.
Eastern Hemlocks can be found widespread throughout New England as far North as Nova Scotia and as far west as Minnesota, However as we move southward it becomes increasingly more restricted to the Appalachian mountains eventually ending in Alabama.
In it's native range, identifying Eastern Hemlock from other conifers is fairly easy, the cones (image 5 from inaturalist) are very small and round, while the needles are dark green shiny smooth on one side and a dull light green on the bottom. The needles come out flat upon the branch, almost like it's 2D when you take a cutting. The bark usually has very thick ridges (Image 7) and the tree has a lovely full triangular form (Image 10) at any age. There is only one other Tsuga species within the same range and that's Carolina Hemlock (Tsuga caroliniana), those are generally restricted to the western Carolinas, the needles protrude at any angle from the branch and cones have a type of curled spike. (taxonomy-wise they are not in the same series which is odd)
Eastern Hemlock is a long lived species, prior to the introduction of the Wooly Adelgid it was not uncommon to find groves of large trees way over 120+ feet and over 300 years old together. While more northern populations generally tend to be impressively large (Image 6 from Delaware Water Gap), Eastern Hemlock reaches its largest sizes south of Pennsylvania. Specimens in the Smokies still reach a staggering heights of 170' and ages above 500 years (Image 7 Below: Cheoah by Will Blozan). While this isn't as Impressive as its western counterpart Tsuga heterophylla which can reach an insane scale of 270', it is staggering for a tree which faces much hotter temperature conditions.
Just about all of the old growth Hemlocks in Appalachia have disappeared, but there are still old growth forests in Northern New England where the Adelgid hasn't really taken hold. Old growth groves do still exist in treated/cold winter/protected areas and somewhat thrive, I visited quite a few during my time in Pennsylvania. I believe the current species 'champion' is in the Allegheny Plateau.
So what is the Adelgid? It is an introduced aphid-like insect which appears as a wooly white growth on hemlock branches. They seems to kill older trees while younger trees are able to cope with it for a time, unfortunately these sap suckers have eradicated old growth stands throughout the Southern Appalachia. I made a post about my childhood forest loosing all of their giants years back, let me tell you it is a much different environment.
Ecologically speaking, Hemlock serves an incredibly important role in stream health. Growing on literal cliff faces this tree is also wonderful at preventing erosion. The dark evergreen shade of hemlocks not only reduces stream temperatures but retains moisture in the height of summer (image 8). it protects streams from extreme weather in winter too (Image 9). cooler stream temps serve as favorable breeding grounds for a higher diversity of stream species while also creating a refuge in winter cold.
If one wants to find moisture loving salamanders and newts in the east it is very common to find large numbers under the hemlock canopy. Tree falls of hemlock serve as fertile ground for fungi and mosses to cover the trunk. Birch and maple saplings often gain a foothold on the soft remains of Hemlock trees whose wood degrades very fast.
For human usage Eastern Hemlock has an odd history. The bark itself is very rich in tannins, settlers would use it for tanning leather. After the Industrial revolution it was used for railroad ties but today its often ignored or used as paper pulp because of its poor wood quality. As for less commercial functions Hemlock is not really an ideal tree for our consumption, The inner bark can be used as starvation food and the needles are a useful emergency Vitamin C source, However I will warn you that the needles are the least palatable of the edible conifers....
Due to it's poor wood and remote conditions it's not really unusual that so many old growth specimens survived up until the 21st century. Nearly all Eastern forest compositions are influenced by which lumber is most/least valuable.
Last portion - Landscape Value.
Eastern Hemlock in the wild is a beautiful tree in all seasons, naturally the tree will develop into a perfect form on its own, though with Adelgid it has lost popularity as a landscaping tree some people still maintain their trees with a once-every-three-year spraying. There are also many horticultural specimens worth thousands of dollars which have low growing and weeping forms, it is quite a versatile species.
So this has been my piece on the Eastern Hemlock, If you do choose to explore one of the few old growth groves still with us, please clean off your boots and gear. Happy Hunting!