The Eastern Hemlock tree (Tsuga canadensis)

Today I'm going to talk about one of the longest-lived of the trees on Canada's east coast, the Eastern hemlock.  Some of you also might know it as Canadian hemlock, or even as eastern hemlock-spruce.  I'm not a fan of that last name, because it confuses people.  Eastern hemlock is not a spruce conifer!  But speaking of names, this species has a Latin name which I find easiest to remember of all Latin names:  Tsuga canadensis.  I guess that's because I'm a proud Canadian.

Before I get into too much detail about this species, let's start with a photo.  This is a good close-up photo showing just a handful of the several thousand eastern hemlock seedlings that we planted this year (2019).

There are three types of hemlocks in Canada, although they all have very narrow distributions.  Western hemlock and mountain hemlock are only found in BC, and mostly in coastal parts of that province.  I've planted large numbers of both of these species while doing commercial reforestation work on Vancouver Island.  So despite the fact that eastern hemlock is not widely distributed throughout most of Canada, it is still the most well-known hemlock.  It can be found throughout all three of the maritime provinces, and also in southern parts of Ontario and Quebec.  Here's a range map, courtesy of Wikipedia:

It's interesting that eastern hemlock does so well throughout southeastern Canada and the northeast seaboard of the US, considering that most hemlocks thrive in temperate rainforests.  The two west coast hemlocks definitely thrive in the moist areas of the coast, and with the exception of the Ancient Rainforest area east of Prince George, almost all west coast hemlocks grow within a hundred kilometers of the Pacific ocean.

The hemlock family got its name from a perceived similarity between the smell of crushed hemlock (conifer) needles and the crushed hemlock plant, even though the plant is completely unrelated to the conifer tree family.  You may be aware that hemlock is well known as a poisonous plant, but hemlock trees thankfully are not toxic! Incidentally, let me take a complete tangent from this post, in case you're trying to remember where you heard about hemlock plants being poison.  Back in ancient Greece, the famous philosopher Socrates went on trial for corrupting the youth of Athens (encouraging anti-democratic uprisings).  He was tried by an assembly of 500 citizens, the majority of whom decided that he was guilty, and was subsequently sentenced to death by poisoning.  At the execution, he calmly agreed to drink the poison down, and that was the end of him.  Plato and Aristotle, two other historical figures that you might be acquainted with if you've studied philosophy (or are a Monty Python fan), were two of his most famous students at the time.  And incidentally, the poisonous hemlock plant is found in twelve US states.  But I digress.  Let's get back to the conifer.

I mentioned earlier that eastern hemlock trees are quite long lived.  Indeed!  They would make any octagenarian jealous.  It is very common for mature trees to live for 250-400 years, if they aren't knocked down in a bad windstorm.  There is one eastern hemlock in Pennsylvania that is going to hit it's 600th birthday in a few decades.  That's pretty impressive.

On Canada's east coast, mature trees often reach a height of about 30m (100 feet) and the trunk of these trees can often approach 1.5m in diamater (almost five feet).  Our Charles Clark forest reserve property in north central Nova Scotia has a belt through the center of the property with almost twenty acres that hasn't been cut in about a century, and it is full of beautiful mature hemlocks.  This part of the property almost feels like a rainforest when you visit it.  In many parts of the US, hemlock trees are only found at elevations of 600 meters and above (cooler climate), but our Charles Clark property is only about 40m above sea level.

Unfortunately, the eastern hemlock is susceptible to two major pests right now.  The first is an "adelgid" (similar to an aphid) known as the woolly hemlock adelgid.  This insect was introduced to north American accidentally from Asia, and eastern hemlock is not resistant to it.  Canadian hemlocks haven't been hit too hard yet, but the adelgid is really doing a lot of damage to stands east of the Appalachians.  The other problem insect is the hemlock looper, which is a type of moth that eats hemlock (and several other common Canadian trees).  Eastern hemlock is also susceptible to a couple varieties of the Armillaria fungus, which is a widely distributed forest parasite (a small mushroom) that attacks many different species.  However, Armillaria (also known colloquially as honey mushrooms) are generally only a problem for mature hemlock.

Another problem that eastern hemlock have to cope with when they're young is being used as a snack by deer.  Deer populations in urban areas of Nova Scotia have exploded over the past decade.  I don't know if the same holds true for rural deer, but in town, we see them on our front lawns everywhere, and they've caused an enormous amount of damage to cedar shrubs and several dozen other types of small plants and flowers.  Anyway, deer love to browse on tender plants.  They tend to avoid plants with needles (except for cedar, which they love) and they also tend to avoid plants with strong odors or bitter tastes.  Although hemlock is not their preferred diet, they will sometimes snack on young hemlock trees.  Hemlock tea tastes quite bitter, but yet the deer don't seem to mind if they're quite hungry.  Hemlock tea is bitter enough that most tea drinkers would definitely turn their nose up, although it apparently has a lot of vitamin C.

If you're ever looking to plant conifers on the east coast, and the property already has some existing brush or tree cover, consider the eastern hemlock as one of the species to potentially include in your mix.  The eastern hemlock is very shade tolerant - one of the most shade tolerant conifers in Canada.

I'll leave you with a photo of some of our eastern hemlock seedlings:

 

Thanks for reading!

- Jonathan Clark
www.replant-environmental.ca



Replant.ca Environmental is a Canadian company that plants trees for carbon capture and builds community forests.  We also plant trees in national, provincial, and municipal public parks to mitigate damage from wildfires, storms, insects, and forest diseases.  We operate thanks to numerous small contributions from the general public, in addition to larger project sponsorships from businesses and corporations around the world.  If you'd like to learn how to show your support, visit our donations page.  Even if you aren't able to make a contribution, we very much appreciate when people are able to share our posts or our website link on social media, to help spread the word about the work that we're doing!

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