Thom Smith | Naturewatch: How to identify evergreen trees in the area


Q: This may be a dumb question, but how do you tell a pine tree from a hemlock tree?

— Clay, Pittsfield, Mass.

A: Both are evergreens, and at this season, especially attractive additions to the winter landscape while hiking, cross-country skiing or snowshoeing.

If the tree has needles in bundles or clusters of two to five, it is a pine. Five long needles to a bundle says it is a white pine, a native tree. If the tree has even longer needles grouped in pairs, that easily snap when bent, it is a red pine.

Native red pines are uncommon, but are commonly planted. Other pine species are uncommon in this area and include pitch pine, a native, and the widely planted Scotch pine, introduced from Europe. Its needles are roughly 2 inches long, blue-green and twisted. They are set in pairs, and the tree is easily recognized by its orange flaky bark.

The widespread white pine can be used in making candy and flour, as a cooked vegetable, and tea. The easiest to make is tea, rich in vitamins A and C. Wait until spring to harvest and use the light green needles from the new growth.

Eastern or Canadian hemlock is among my favorite trees, providing cool moist fragrant woods during the hottest months, and in winter, shelter from the wind while on an outing. It is easily identified by its needles (leaves) that grow in rows on either side of the shoot. The needles are dark-green on their topside, and are light-green with two white lines beneath.

This species was once used for tanning leather. Hemlock's bark was an important source of tannin, and may still be in places. Native Americans made tea from its needles and in earlier times used the inner bark of this tree to make a bandages to cover wounds and sores. I have yet to try tea from the hemlock tree.

Q: What makes the Monarch butterfly poisonous while most other butterflies are not? I know this happens in other animals sometimes. Why?

— Sally, Bennington, Vt.

A: Monarch butterfly larva feed on the milkweed plant. And, if you have ever broken a leaf off one, you have seen a white viscous liquid coming from within. This milky sap (from which the plant gets its name) consists of latex that contains alkaloids and other compounds including cardenolides, a.k.a. cardiac glycosides because they arrest heart function (stop the heart).

The larva munching on the plant ingests this toxin. A vertebrate animal, such as a bird, eating the butterfly would also ingest the toxin and have a heart attack, I presume. Other plants such as digitalis or foxglove have this or similar compounds.

So reliant upon the milkweed plant, that whenever I see both monarch and milkweeds, I always look for eggs or larvae, but I will reserve that for a column next summer.

The "other animals" you refer to may be the poison arrow frogs of Central and South America that get their poison from ingesting ants, mites and termites. Like the monarch butterfly, many of the poison arrow frogs are brightly colored; a warning to the would-be predator, "Leave me alone."

The Berkshire Museum aquarium has a good assortment of (breeding) poison arrow frogs, that perhaps should now be called arrow frogs, because without ingesting the toxic ants, mites, spiders, termites and the like, they are no longer poisonous. At the museum, the tiny, brilliantly colored frogs get a daily feeding of assorted fruit flies.

Thom Smith welcomes your questions and comments. Email him at or write him care of The Berkshire Eagle, 75 S. Church St., Pittsfield, MA 01201.


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