This week, I want to introduce you to another native evergreen, one that is just as graceful and often grows side by side with white pines: Tsuga canadensis, the Eastern Hemlock. Although hemlocks are also very tall, their details offer a beautiful contrast with white pine. Where white pine has long soft needles in bundles of five, hemlock has short, flat needles that stick out on either side of its twigs, creating a feathery impression. Hemlock cones are much smaller than those of the white pine, measuring ½ -1 inch and sport gently rounded scales. White pines may drip with fragrant and sticky resin, but not hemlock.
Turning a hemlock needle over, you will find two white lines. These are chains of pores or stomata, with which the leaves “breathe”. Hemlocks are under attack by the non-native wooly adelgid that can kill a tree after several years. Adelgids resemble tiny bits of cotton and can be controlled with horticultural oil spray. Unfortunately, this is not feasible in forested areas and researchers are investigating other types of control.
The first hemlock I ever heard of was the poison variety that the classical Greek philosopher Socrates was condemned to drink. But these two hemlocks are not related at all. Poison hemlock (Conium maculatum) is a member of the carrot family. This illustrates one challenge of using common plant names: they change from place to place and different plants may bear similar names. Hence the importance of the scientific naming system, in which each organism is given a unique name that also indicates its relationship to other organisms.