How to identify hemlock trees

Look for deep shade

Hemlocks often grow together in dense stands along streams and cool, north-facing slopes.

Their canopies block sunlight and create deep shade that keeps soil moist, the water table higher and streams cooler.

These cool, wet conditions are great for insects and macroinvertebrates that fish depend on. In fact, streams surrounded by hemlocks have about three times as many trout as streams in deciduous forests.

Unlike other trees, hemlocks grow more in spring and fall (and even winter) and partially shut down in the summer. This allows them to avoid water stress during the hot summer months.

Identify hemlocks by looking for furrowed brown bark

Hemlock bark is distinct and a great way to identify the trees, It’s light brown with deep furrows. The only tree that has similar bark is white pine, but white pine bark is darker and thicker.

If you peek under the outer bark, you’ll see a reddish-purple color. This color makes it a favorite for landscaping mulch. The tannins derived from hemlock bark were used commercially to tan hides from the early 1600s until the early 1900s.

Purple-colored inner bark of a hemlock

Is it hemlock or balsam?

Hemlock needles are similar to balsam fir. Both have short, soft, flat needles with two white stripes underneath.

One way to tell them apart is the length of the needles. Hemlock needles are usually about 1/2 inch, while balsam fir needles are closer to 1 inch.

Still not sure?

Also take note of how the needles are attached to the twigs.

Hemlock needles are attached by soft stems, while balsam fir needles look as if they are attached by suction cups.

And of course, if you still aren’t sure if you are looking at Hemlock or balsam, try crushing the needles and see if you smell that classic balsam smell.

Keep an eye out for fuzzy white stuff

If you find white fuzzy stuff around the base of the needles, you may be looking at a hemlock woolly adelgid infestation (HWA).

This invasive insect is killing hemlock trees in Windham County and has been found in Windsor and Bennington counties.

With warming winters, the hemlock woolly adelgid seems to be heading north.