Hemlock

Several weeks ago we watched for the umpteenth time, The Rose Rent, one of the few DVDs that we own. Derek Jacobi stars masterfully as Brother Cadfael, in this PBS Mystery! series, set in 12th century Shrewsbury. Cadfael is less extreme in his religious views than other monks in the Shrewsbury Abbey, and he is an herbalist, skills he often uses to solve mysteries. This episode begins with Cadfael giving a potion to a woman whose husband is dying in extreme agony. The potion is some sort of poppy extract, but this time with "hemlock," which Cadfael warns, "one thimbleful Judith dulls the pain, two thimblefuls dulls the pain forever."

Cadfael had gathered poison hemlock, Conium maculatum, a plant native to Europe. Since the 1800s the plant has grown and spread throughout the U.S. A member of the parsley family, it is a perennial that grows in roadsides, stream banks, field edges, and other disturbed sites. And it is poisonous.

Today though I am thinking about a completely different hemlock -- the eastern hemlock, Tsuga canadensis. One of our most common forest trees in New England and one of my favorites.

Eastern hemlock cones and needles

Hemlock is the most shade tolerant and longest-lived of all tree species in the eastern U.S. It can grow suppressed in the understory for 400 years, before a sunlit gap in the forest finally allows it to put on a growth spurt. The cones are small, much more diminutive than the cones of its common neighbor in the forest, the white pine. Hemlocks are scattering their wind-dispersed seeds now and into winter. The needles are short, soft, and flat, with two white lines on the underside.

Single hemlock trees grow scattered throughout our oak-pine and hardwood forests. Most often though, you notice hemlock where it grows in pure stands, forming a dense canopy overhead. Beneath the thick canopy of hemlock, the forest is dark and sparse. In winter, thick hemlock boughs prevent snow from reaching the forest floor. White-tailed deer spend winters here, where it is easier for them to move around. Porcupines also like hemlocks -- chewed hemlock branches scattered on the snow is a sure sign that this mammal is out and about.

Porcupine-chewed hemlock branches.

Two warblers are fond of hemlock forests -- listen for their songs overhead as you walk through a cool, hemlock-shaded forest in June. Since that is a ways off you have time to learn the songs of the black-throated-green warbler ("zoooo zeee zo zo zeee") and the blackburnian warbler (a thin, high-pitched "tsi tsi tsi tsi ti ti ti ti tseee"). I often hear barred owls calling "who cooks for you" and see pileated woodpeckers in our local hemlock forests. A chattering red squirrel is another common denizen.

A small sap-sucking insect native to Japan and China is killing eastern hemlock from North Carolina to Maine. So far, it has killed few hemlocks in New Hampshire. One thought is that colder temperatures here keep it at bay. But temperatures are changing, and the adelgid is advancing, both on the wind and stuck to the feathers of birds. In New Hampshire, Maine, and Vermont, homeowners and nurseries cannot bring hemlock seedlings or trees from adelgid-infected states, unless certified as pest free.

Winter will soon be upon us. The x-country skis and snowshoes are ready for the season's first good snowfall. When it arrives we will head out on trails that wind through hemlock glades, snow deep in the trail. Hemlock boughs on either side laden with snow bowed down to the ground. Snowshoe hare tracks criss-cross the trail, the hares keeping safe beneath the thick greenery. All sounds of the outside world muffled by snow and hemlock.