Wildlife Research, Monitoring & Mentoring

Why You Should Worry About Miscanthus

You’ve seen Miscanthus. Even if you don’t know it by name, you’ve seen its tall, feathery seed heads and arching green leaves with white midribs. You’ve noticed this ornamental grass planted in manicured residential yards across the island, at businesses, at driveway entrances, or piled into the beds of landscaping trucks. You might also have seen it popping up along roadsides, in fields, and along forest edges, escaping cultivation. To a Vineyard ecologist, that’s worrisome.

Miscanthus is a genus of grasses that are native to Eurasia, Africa and the Pacific Islands. In New England, two species of East Asian origin that were introduced as ornamentals have become naturalized, meaning that they now grow and reproduce on their own in the wild: Miscanthus sinensis, commonly known as Chinese silvergrass or maiden grass, and Miscanthus sacchariflorus, known as plume grass, Amur silvergrass, or Japanese silvergrass.

Miscanthus sacchariflorus

Here’s the problem: the Massachusetts Invasive Plant Advisory Group (MIPAG) evaluated M. sacchariflorus and deemed it a likely invasive – that is, a non-native plant poised to cause ecological harm by spreading rapidly, growing aggressively into dense monocultures, and out-competing native species. As a result, M. sacchariflorus is now included in the Massachusetts Prohibited Plant List, which bans the importation, sale, or trade of plants deemed invasive. So far, so good.

Miscanthus sinensis

However, land managers also report seeing M. sinensis regularly escaping cultivation and invading natural habitats. On Nantucket, in particular, this species has been observed spreading into native grasslands and heathlands. But when MIPAG evaluated this species, they lacked sufficient documentation of its spread to officially include it in the invasive plant list. While there’s ample anecdotal evidence that it’s out there, MIPAG needs more hard evidence in the form of photographs or other proof before the species can be listed.

The stakes appear to be high, especially for the globally rare habitats occupying the sandy glacial deposits that constitute Cape Cod and the Islands. At a recent conference of the Sandplain Grassland Network, a collaboration of land managers who steward these precious ecosystems, a presentation by Dr. Jenica Allen of UMass Amherst outlined how climate change can amplify threats posed by invasive plants. For one thing, an increase in temperature and carbon dioxide will give invasive plants a disproportionate advantage over native plants. Likewise, many species will experience shifts in phenology, or biological timing, emerging earlier or persisting later in the growing season (or both). These shifts are also likely to disproportionately benefit aggressive exotics. An increase in disturbance caused by extreme weather events will create new opportunities for the spread of invasive plants. Finally, many species will experience range shifts, moving farther north as the climate warms. Dr. Allen’s team identified the Northeast as a future hotspot for plant invasions: Many warm-climate invasive species will expand northward, and other non-native plants that are already established here, but not currently exhibiting invasive tendencies, will become more troublesome in future climatic conditions.

M. sinensis on Long Island

This presentation was followed by a talk by Bill Jacobs and Kassidy Robinson of the Long Island Invasive Species Management Area which identified emerging invasives in grassland habitats. Their talk identified both M. sacchariflorus and M. sinensis as newly emerging threats on this island just to our south, which shares the Vineyard’s glacial origin and sandy soil types. In addition to their tendency for dense growth, both of these grasses are highly flammable. Despite their popularity as landscaping plants, in other words, both of these non-native grasses seem particularly likely to pose ecological problems in the Vineyard’s most valuable native habitats.

Here’s how you can help. In order to get M. sinensis listed as an invasive and included in the Massachusetts Prohibited Plant List, more documentation is needed. If you see Miscanthus growing on a roadside or otherwise escaping cultivation, make sure to photograph it and upload the photo to a platform such as iNaturalist or iMapInvasives. You’ll need a few hints to help distinguish the two species: M. sinensis has a small, needle-like bristle called an awn attached to the flower structure; this awn is absent or reduced in M. sacchariflorus. Both species have white hairs in their inflorescence, but these hairs are longer in M. sacchariflorus, giving the flower head of this species a lighter appearance. And while both species spread by rhizomes (horizontal underground stems that sprout new growth), rhizomes of M. sinensis are shorter, giving this species a more densely-clumped growth form.

M. sinensis awn

But you don’t need to be a botany expert to help. iNaturalist, for example, deploys both artificial intelligence and crowdsourcing to help with species identification. If you’re unsure which species of Miscanthus you’re seeing, you can simply upload the photo and leave it to the experts to make the ID. Just make sure to get a good close-up of the seed head, as the presence or absence of the awns can be a distinguishing feature.

Miscanthus leaves

Meanwhile, there are steps you can take to prevent further spread of these species into surrounding habitats. Because the Prohibited Plant List only bans the sale of invasive species and does not cover existing plantings, it is likely that M. sacchariflorus is still growing widely across the island. If you have Miscanthus growing on your property, consider digging it up, or, at minimum, removing and disposing of the seed heads each growing season. Politely encourage others to do the same. You can plant native alternatives such as switchgrass (Panicum virgatum), big bluestem (Andropogon gerardii) or Indian grass (Sorghastrum nutans), tall bunch grasses that combine visual appeal with ecological benefits. Finally, you might urge landscapers and local nurseries to stop selling Miscanthus and instead stock native alternatives. Consumer demand can drive change in the absence of state regulations.

One final point: with so many problems in the world, it’s easy to wonder why you should worry about Miscanthus, or any other invasive species. I would argue, though, that Miscanthus is a worthy cause because it is a solvable problem. In the invasive species management world, there is an approach called “early detection, rapid response”. Put simply, it means that it is much easier to control an invasive plant infestation while the population is still small. Right now, it seems that we are at a critical juncture with Miscanthus: we know it’s invading natural habitats, but if we act quickly, we have a chance to address it before it becomes a much more widespread and expensive concern.

It’s important to remember the powerful ecological role that plants play. As the basis of the food chain, plants provide sustenance for all other creatures. Our local wildlife co-evolved with native plants and often don’t identify exotic species as food. By protecting our native flora from the threat of invasives, we will also sustain the greater web of life that’s interwoven with our botanical neighbors.

Looking for advice on ecologically-friendly landscaping practices? To join our free Natural Neighbors program, complete the survey at https://biodiversityworksmv.org/programs-projects/natural-neighbors/.

Want to help prevent the spread of non-native invasive plants? Contact Rich Couse at rcouse@biodiversityworksmv.org to become an Invasive Plant Brigade volunteer.

<a href="https://biodiversityworksmv.org/author/jsepanara/" target="_self">Jennifer Sepanara</a>

Jennifer Sepanara

Position

Jennifer wore several hats for BiodiversityWorks in 2023. You could find her surveying insects on eight island farms for the Pollinator Pathways project, assisting with outreach for the MV Atlas of Life, or most recently, coordinating Invasive Plant Brigade volunteers for the Natural Neighbors program. An island native, Jennifer has worked for conservation organizations from Maine to New Jersey.

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