11/7/2024: Green in November: American Holly and Canada Hemlock

American holly (Ilex opaca) is a broadleaf evergreen with a wide native range from the Eastern to Central United States. This common feature in holiday wreaths has several other common names, such as Christmas holly, Yule holly and prickly holly. It blooms clusters of cream flowers in May that, while small and easily missed in a garden, attract many bees and other pollinators. Most people are more familiar with its later season’s visage. The vivid crimson berries against a backdrop of deep green, spiky foliage give this holly a distinctive and memorable appearance tied to winter festivities.

While certainly pretty, the amount of American holly present around our various winter holidays must suggest an expansive cultural history. Indeed, because of its similarity to English holly (Ilex aquifolium), settlers attributed to it the same traditions from their original homelands in Europe, especially Germany. Since evergreens such as holly persist throughout the cold, they symbolize surviving life and an enduring spirit that outlasts winter. Because of its bright berries, American holly is associated with the solstice: the return of light to the dark.

This holly grows naturally in moist woodlands, forests and along streams. It can tolerate many soil conditions so long as it’s well drained, and it will thrive in full sun to partial shade depending on your home (if you have more sun, partial shade in the afternoon is best). This beautiful native will not only give your woodland gardens and hedges an elegant splash of color, the berries are a wonderful winter food source for birds such as cedar waxwings (Bombycilla cedrorum) and other wildlife like Eastern gray squirrels (Sciurus carolinensis). It also provides key shelter against the harsh winds for wildlife.

The elegant state tree of Pennsylvania, Canada hemlock (Tsuga canadensis)—also known as Eastern hemlock—is an evergreen distinguished by flat needles growing from thin branches. Their beautiful blueish-green foliage presents an amazing contrast against snowy scenery, and the little cones drape like delicate decorations. Unlike the similarly named herb, poison hemlock (Conium maculatum), a traditional tea was safely brewed from the Canada hemlock's needles and bark. It also had medicinal uses as wound treatment and a skin wash.

Not only is it an attractive native tree for ornamental gardening, Canada hemlocks are very shade tolerant and do well in acidic soils. According to the National Park Service, they are astoundingly long-lived and may reach 1,000 years, and they provide habitat to many wildlife species like squirrels, mice and songbirds.

This magnificent species is currently in danger from an invasive pest, the hemlock woolly adelgid (Adelges tsugae). The adelgids are difficult to spot, but their bright white and fuzzy egg masses can help identify their locations.

You can find eastern hemlocks all throughout the Preserve, and there is a grove of them on the Azalea Trail.