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Swap out invasive ornamentals for island-native species that support local wildlife.
Robyn Graygor is the Biodiversity Technician for BiodiversityWorks’ Natural Neighbors program on Martha’s Vineyard. This article originally appeared in our Martha’s Vineyard magazine and has been edited and adapted for a Nantucket audience, thanks to Stacey Cooper and Kelly Omand of the Nantucket Conservation Foundation.
If you want to help maintain Nantucket’s iconic native plant communities, consider planting island-native species in place of their invasive knock-offs.
Common problem plants and their native alternatives:
1. Miscanthus
Grasses in the Miscanthus genus have become popular ornamental plantings across the eastern United States. Specifically, Miscanthus sinensis has risen the ranks in the nursery trade, leading to many properties and public landscapes being stamped with their signature dramatic appearance. Billowing grassy tendrils with a silver vein form satisfying plumes that complement textures in traditional gardens. Cultivars like zebra grass have made their way into many landscape designers' hearts; striking foliage with sharp yellow bands wins over even the most grass-hating gardeners.
This perennial bunchgrass can succeed in a variety of conditions. It is found in edge habitats, gardens, grasslands, coastal zones, and anthropogenic areas like roadsides and ditches. It can thrive in full sun to part shade, and it spreads readily by both seed and rhizomes.
Large tufts can grow up to 10 feet tall, overshadowing and crowding out the Island's iconic native bunchgrasses. Widespread infestations threaten to monopolize meadows and leave habitats more susceptible to the stresses of climate change. Chinese silvergrass (Miscanthus sinensis), for instance, is highly flammable and increases the risk of wildfires as its dense stands dry out.
Native alternatives
Nantucket is home to several native bunchgrasses that decorate meadows, provide food for birds, and host native butterflies like the Crossline Skipper. A great source of protective cover and nesting material, these grasses will fill space elegantly while helping to maintain the globally rare ecosystems found on the Islands. Switchgrass (Panicum virgatum) is the most similar to Chinese silvergrass, with its tall tufts and dramatic seed heads. But nutritious switchgrass seeds will be eaten by birds in the fall and winter, whereas Chinese silvergrass seedheads are often left unused. Consider planting the following grasses in place of invasive grasses in the Miscanthus genus:
- Switchgrass (Panicum virgatum)
- Indian grass (Sorghastrum nutans)
- Big bluestem (Andropogon gerardii)
2. Privet
Privets (Ligustrum spp.) are found in all shapes and sizes. Most commonly, border privet (Ligustrum obtusifolium) decorates property lines as sculpted hedges. These prized privacy barriers were introduced to North America in the 1800s. Fast growing and resistant to rust (a type of leaf spotting), their simple semi-evergreen leaves offer dense coverage throughout the seasons.
The same characteristics that have made this shrub so sought after have also allowed it to become a successful invasive offender. Mature shrubs produce hundreds of seeds that are dispersed by birds and wildlife well into the winter. New plants can also arise through root sprouts and suckering. Toxic compounds in the leaves deter deer browsing and some leaf-feeding insects. Privet is able to outcompete native shrubs and hinder the development of surrounding vegetation with its dense stands. The resulting shady conditions can interfere with forest regeneration while favoring the growth of more privets.
This plant’s readily available fruits are junk food for birds, passing through their digestive tracts quickly while providing mainly sugar and water. Specialist insects that have developed intricate relationships with specific plants are threatened when this aggressive spreader takes root in native ecosystems. Privets can be found in all regions of Massachusetts, under various growing conditions, making most any vegetative community susceptible to infestation.
Native alternatives
Several island-native shrubs work well in a hedgerow or in other manicured shapes. These species can bring a tinge of intentionality to a landscape while also servicing native birds, insects, and wildlife. Inkberry (Ilex glabra) is an evergreen shrub in the holly family that provides dense screening. It looks similar to a boxwood, and can be sculpted with pruning. Similarly, a mix of arrowwood (Viburnum dentatum) and sweet pepperbush (Clethra alnifolia) grow happily in a mosaic hedge formation. If you are looking to replace your privet with a native shrub, consider planting one of the following:
- Inkberry (Ilex glabra)
- Sweet pepperbush (Clethra alnifolia)
- Bayberry (Morella caroliniensis)
- Arrowwood viburnum (Viburnum dentatum)
3. Chinese & Japanese Wisteria
Both Chinese wisteria (Wisteria sinensis) and Japanese wisteria (Wisteria floribunda) decorate trellises, gazebos, and gardens with clusters of light purple flowers. Some people even create dedicated wisteria gardens to show off the vine’s unique beauty. However, introducing wisteria to a property can become a lifelong commitment: this commercially available woody vine is a long-lived perennial, surviving for 50 years or more.
Chinese wisteria was introduced to the United States in 1860 as an ornamental planting, and Japanese wisteria was introduced in 1830. Both thrive in deep, loamy, well-drained soils but can successfully grow in a variety of conditions.
Wisteria easily escapes from yards and infests wild areas from the forest floor to the canopy. The trailing vines twine clockwise and can climb up tree trunks over 60 feet tall, so it can become an unwelcome guest rather quickly in your yard. The trunks of mature plants grow to be over 15 inches in diameter, eventually girdling and killing their hosts. New vines arise from the nodes of trailing stems that stretch great distances. Under the right conditions, the plants also produce seeds, which explode from their pods and can be dispersed by water flow. As new plants sprout from seeds or vegetatively, they open broad compound leaves that shade surrounding areas like a carpet across the forest floor.
Managing a wisteria infestation can be a long, grueling process. Although wisteria is not officially recognized as an invasive species by the state of Massachusetts, it is in Connecticut.
Native alternatives
The island harbors several native vines that are hardy additions to a trellis or other suitable surfaces. Grape vines (Vitis spp.) are fast-growing and full coverage options that will dangle bunches of fragrant, dark purple grapes in the fall. Consider planting one of our island-native vines as both an aesthetic addition to your property and a resource for local wildlife.
- Summer grape (Vitis aestivalis)
- Fox grape (Vitis labrusca)
- Virginia creeper (Parthenocissus quinquefolia)
4. Sycamore Maple
Sycamore maples (Acer pseudoplatanus) grow into large majestic shade trees that are tolerant of Nantucket’s harsh coastal conditions. Once established, their seed spreads readily and helps them to form dense thickets that outcompete native plant species.
Often seen as a street tree in downtown areas, the flaky bark and large leaves provide the essence of a typical New England maple tree without providing the ecological benefits of our native maples.
Native alternatives
Finding a native replacement for Sycamore maple is simple: plant red maple (Acer rubrum) instead! This tree is easy to grow in a variety of conditions and displays dazzling fall color. Its early bloom welcomes a myriad of native bees in search of nectar, as well as birds who frequently nest and search for food nearby. Various native moths and butterflies use this tree as a host plant, including the iconic rosy maple moth (Dryocampa rubicunda).
- Red maple (Acer rubrum)
- Black gum (Nyssa sylvatica)
5. Japanese Black Pine
These pine trees (Pinus thunbergii) were introduced to the island to provide a fast growing evergreen species to block wind and provide screening. Coming from another island environment, Japan, it was assumed they would do well in Nantucket’s harsh coastal climate. The trees quickly established as they produce thousands of seeds and thrive in our sandy soils. Unfortunately, they form dense groves and outcompete our native trees and shrub species as well as encroach on our rare open sandplain grassland communities. The trees have proved to be susceptible to native insect pressure and therefore short lived on the island, creating fire hazards with stands of trees dying off, but with dense thickets of saplings beneath.
Native alternatives
The stand out alternative for our island environment is the native pitch pine. This species was once extirpated from our island and reintroduced in the 1800’s, however it is in sync with many of our native insects and provides much needed habitat for endangered bat species. While the Japanese black pine declines with age, our native Pitch pines can live for over a hundred years, providing a significant component of our forest canopy on the island. Pitch pines are susceptible to southern pine beetle damage when found in dense stands, but remain healthier in scattered plantings.
- Pitch pine (Pinus rigida)
- Red cedar (Juniperus virginiana)
- American holly (Ilex opaca)
Resources
While there is a growing interest in sourcing native plants, it can be difficult to find seed and nursery stock native to specific environments. When shopping for native plants prioritize wildtype plants native to Nantucket, Cape Cod, or coastal ecoregion 84 when possible. The genetics of these plants will be best adapted to our coastal conditions and in sync with our native wildlife. You can order native seeds online from the Wild Seed Project website or Ernst Seeds. Island growers such as Surfing Hydrangea, In Situ Native Plant Nursery, and Nantucket Conservation Foundation are all expanding their offerings of native plants.
The Native Plant Trust has a database called Go Botany that can be used to determine which species are island-native and which are not. If you need assistance identifying the plant life that exists on your property, iNaturalist can be a helpful tool. Upload images to iNaturalist and receive several computer generated recommendations on what the species might be. Then, wait for seasoned naturalists to review your post and either verify your identification or suggest otherwise.
The Native Plants for Nantucket pamphlet, list species native to the island along with the conditions in which they prefer to grow. This was developed by Nantucket Biodiversity Initiative and is available in hard copy at NLWC and at NCF, as well as online. Click here to view the pamphlet.
Takeaways
Native plants form intricate relationships with local wildlife, birds, and insects that have evolved alongside them. A healthy ecosystem requires balance and biodiversity to remain beneficial. Invasive vegetation is like a misfit cog in the machine, a part that doesn’t benefit the function of the landscape. Without natural predators or equivalent competition, invasive plants cause tremendous damage to ecosystems and the insect and animal communities that rely on them.
Planting native species in place of these invasive plants can help maintain the unique natural beauty of the place we call home. It’s time we start rooting for the home team!
