by Sarah Treanor Bois, Director of Research & Education for the Linda Loring Nature Foundation
Unlike the rest of New England, Nantucket is not particularly known for its fall colors. People travel to Nantucket in the fall not for leaf peeping, but for the warmer maritime climate, the fishing, and weddings. And while there are some beautiful fall colors just waiting to show their stuff, beware the nonnative invasive species. Some of these showy invaders may look pretty, but their invasive tenacity can pack a punch. Looks, after all, can be deceiving.
Oriental Bittersweet (Celastrus orbiculatus) is one of the worst invaders in New England. The woody climbing vine is native to Eurasia, where lianas (or woody vines) are common. This climbing powerhouse can girdle trees, shade out natives, and generally take over any patch of ground or sky. The bright orange and red fruit burst open in the fall, making it a favorite of decorators everywhere. Martha Stewart still recommends making wreaths for decorations even though the plant is officially listed as invasive in all six New England states. Seeds of bittersweet are spread when the plants in the arrangements are later thrown away. Birds love the fruits, too, and help to disperse far and wide the seeds which will grow almost anywhere. Beware the bittersweet wreaths! Save yourself a landscaping headache and get a fake wreath if you must. Otherwise, the decorations you thought looked sweet in October will leave a bittersweet taste in your mouth come December.
Burning bush (Euonymus alatus) is widely planted as an ornamental shrub throughout the country. Its gorgeous fall foliage of fiery red gives it its name, but also its popularity. At one time, it was heralded by many conservation groups as a great shrub to plant to attract birds. The fruits are ideal for migratory birds as they are held onto the plant well into the fall and winter. For this same reason, birds have helped distribute this plant far and wide well away from the cultivated areas where they were first planted. Now that we know more about its invasive tendencies, please avoid planting this in your yard and opt instead for native sumac or sassafras.
Another fall favorite is Japanese barberry (Berberis thunbergii). The small, leather tear-shaped leaves turn bright red in the fall. The tiny red drupe fruits are also an eye-catching, hanging onto the plant late into the season making for a showy perennial. While it may sound nice, Japanese barberry has been in the news a lot for being a hotbed of tick activity. Not only is this Asiatic shrub highly invasive throughout New England, it provides ticks with ideal habitat. Like many invasive shrubs, Japanese barberry holds it leaves on late into the fall and winter. In doing so, it creates a humid environment that ticks love. Deer tend to eat around it, avoiding it in preference on native shrubs and wildflowers. This created more opportunity for barberry to grow and more habitat for ticks to hide out in. I think we can all agree that anything that increases deer tick habitat needs to go!
If you’re not into fall foliage, fall flowering plants may be more your cup of tea. Sweet autumn clematis (Clematis terniflora) is an herbaceous vine that likes to grow up and over picket fences, arbors, and other shrubs. As the name implies, the tiny white flowers blossom in the fall and have a delicate, sweet fragrance. It can also tear down your arbor, white picket fence, and kill the shrub it’s smothering. Sweet autumn clematis is native to temperate regions in China and Japan, but has become naturalized in many parts of North America. While not everyone considers this plant invasive, there are some other great alternatives that would be better than planting this invader. For many years, the freezing temperatures of a New England winter have helped keep this plant in check. However, with global climate change and warmer winters, clematis has become more of an invasive problem especially on Cape Cod and the Islands.
Another non-native invasive that is on the rise on Nantucket is porcelain berry (Ampelopsis glandulosa). This herbaceous vine can now be seen at Squam Farm, Lily Pond, and many other conservation properties on the island. As a relative of grape, the vine and leaves resemble our native fox grape. However, porcelain-berry leaves are much more highly lobed. Not really known for its foliage or flowers, porcelain-berry fruit can be seen in autumn and resemble multicolor Cadbury eggs. The round, speckled fruit come in shades of baby blue, light pink, and purple. Much like oriental bittersweet, porcelain-berry climbs on and over native plants. Migratory birds especially like these fruit and further spread the seeds beyond the local area.
While attractive, these non-native invasive plants can cause economic and environmental harm. They are like some of the good-looking people one meets (you know the type): once we get past the exterior, we realize we wouldn’t necessarily want them hanging out in our yards.
Beyond these non-native invasives, there are many other plants to admire in the fall on Nantucket. The shrublands of the middle moors and western end of the island will turn crimson as the native black huckleberry bushes change into their fall foliage. The tupelo trees of Squam Swamp will brighten to crimson as the season progresses. Even the evergreen trees of the state forest will seem to brighten as the poison ivy and Virginia creeper climbing up their trunks redden.
For more information about planting natives in your own yard, check out the Nantucket Biodiversity Initiative’s Invasive Plant Species Committee website. There you’ll find a downloadable brochure on Nantucket landscaping with native plants.