Few plants evoke winter holidays in the north more dependably than the Christmas holly (Ilex aquifolium). The plant’s handsome evergreen leaves and red berries have enjoyed a sacred place in European cultures, from the British Isles to the Mediterranean, since classical antiquity. Today, it remains the member of the holly family (Aquifoliaceae) most likely to festoon mantels and doorways in celebration of the season. But while Christmas holly originates across the Atlantic, our region has two native holly species of which to boast – and they do much more on the landscape than brighten homes and spirits at yuletide.
You can find northern New England’s hollies in their preferred habitat in bogs, swamps, and other waterlogged areas. The two shrubs – mountain holly (Ilex mucronata, formerly Nemopanthus mucronatus before genetic testing prompted a reclassification) and common winterberry (I. verticillata) – are common in wetland complexes or their edges, where they can reach 15 feet tall. The species tend to intermingle in these settings, which can make distinguishing them a challenge.
Luckily, there are several differences between the two that can help aspiring holly honchos tell them apart, even in the cold months. One is the specific locations in which they grow. Though both are wetland plants, mountain holly can tolerate drier conditions than its counterpart; in wetlands hosting both species, you might find mountain holly along the periphery, rather than in standing water like winterberry. You may also come across mountain holly, as its name suggests, growing at higher elevations than winterberry.
Another key distinction lies in the fruit of the two species. Both plants are dioecious, meaning that every individual is either male or female. When fertilized by the pollen of a nearby male, females of both species produce the attractive red berries – technically drupes, or fruits consisting of skin and flesh that surround a pit containing the seeds – for which the holly family is widely known. But mountain holly berries are about 1/3-inch wide, hang from thin stalks like cherries, and according to the University of Maine Cooperative Extension, are usually snapped up by wildlife before winter rolls around. Winterberries, meanwhile, grow in clusters tight to the shrub’s branches and rarely exceed 1/4-inch in width. They almost always persist far beyond fall, firing winter’s drab palette with spellbinding pageants of red.
That is, until non-human eyes discover them. It is a delightful annual ritual to behold the bedlam of a hungry flock of robins dropping out of the sky into the humble grove of winterberries in a swampy area of my yard. Males and females dangle from the waist-high shrubs like top-heavy ornaments, their wings flapping for balance, and gobble up the berries in their immediate vicinity before contorting themselves to pluck those on neighboring branches. Berries go down the robins’ speckled gullets in one gulp – first pinched in their beaks, and then, with a toss of their heads, sliding into their bellies.
What remains after these raiding parties will feed a suite of wildlife. In addition to robins, 47 species of birds eat winterberries, among them northern mockingbirds, cedar and bohemian waxwings, and eastern bluebirds, according to the Natural Resources Conservation Service. The little morsels are comparatively spartan pickings compared to seeds and insects, but when winter deepens and those calorie-dense foods diminish, winterberries offer a critical nutritional backup. (Hungry hikers tromping through a snow-covered bog should look but not eat; winterberries are mildly poisonous to humans.) Sated winged and four-legged diners, which include mammals from bears to squirrels, propagate the species by spreading the seeds over the landscape in their droppings. Twigs of both shrubs are also fodder for deer and rabbits.
Alas, this impressive wildlife value cannot neutralize our two native hollies’ aesthetic Achilles heel. Christmas holly’s leaves persist through the winter alongside the berries, creating the eye-pleasing combination associated with year-end holidays. Mountain holly and winterberry, on the other hand, are deciduous; they drop their leaves in the fall. Though leaf-drop accentuates the spectacular display of berries, it puts our native Ilex species at a disadvantage when competing for decorating prominence with the red-and-green allure of Christmas holly.
Still, winterberry and mountain holly crack on, outside, as stalwarts of northern New England’s winter ecology. More native berries for the birds!