Weed of the Season: Wavyleaf Basketgrass
Non-native invasive Wavyleaf basketgrass has been spotted along trails in Baltimore City, lying in wait for unsuspecting passersby to pick up its tiny, gooey seeds and transport them to new areas. Learn how to identify it and help prevent its spread!
A small patch of wavyleaf near Loch Raven Reservoir | Photo: T. Brann
What is wavyleaf basketgrass?
Oplismenus undulatifolius, more commonly known as Wavyleaf basketgrass, is a low-lying, trailing perennial grass first discovered in the U.S. growing in small patches along a trail in Patapsco Valley State Park in the mid-1990s. Nobody quite knows how it got here, but within a decade, it spread to cover thousands of acres of public and private land in Maryland and Virginia. In 2016, it was also found in Pennsylvania. While many park and natural resource managers in Maryland have made wavyleaf control a priority, lack of funding has made it difficult to contain populations, so community awareness is vital in preventing its spread to new locations!
Where is it in Baltimore City?
Wavyleaf has been spotted in Gwynns Falls Leakin Park along Former Wetheredsville Rd, north of Winsdor Mill. This infestation is fairly extensive, growing along the edge of the trail in multiple locations and encroaching into the forest interior. Two additional locations have also been found on a trail near Carrie Murray Nature Center and on the Conservation Trail. These patches are small and can still be contained with minimal management.
Other small patches have been found on city property along a trail near the northwestern portion of Loch Raven Reservoir.
The largest infestation identified in the city follows the Former Wetheredsville Rd Trail north of Windsor Mill
What does it look like?
The leaf blades are flat, dark green in color, about ½ inch wide, and 1 ½ to 4 inches long. It gets its name from its distinctive leaves, which have a rippling appearance. The leaf base touches the stem without encircling it, and leaf sheaths are noticeably hairy.
It branches from the base with long, trailing horizontal stems that take root at points along its length to form new plants. Each plant is usually under 18 inches. The stem is covered in grandpa-whisker-like white hairs.
It typically blooms in mid-September to November, though some plants may flower earlier. Flowers occur at the tip of the plant, with a 4 inch branching cluster of flowers and feathery white stigmas. Seeds come in 3-5 pairs of spikelets, each armed with a ½ inch bristle that becomes sticky with a glue-like substance.
Note the hairy stem, rippled leaves, and bristled seeds | Photos: T. Brann
But it’s so pretty! Why is it a problem?
Wavyleaf is still being studied, and it’s unknown what its long-term impacts will be, but ecologists believe it has the potential to become even more widespread and damaging than Japanese stiltgrass.
Causes for concern:
- It loves shaded areas, preferring to grow in the understory, and it can penetrate deep into the interior of forests.
- Its perennial life style allows it to emerge, year after year, through thick leaf litter, giving it the opportunity to take over areas inaccessible to annual invasive grasses like stiltgrass.
- It spreads quickly through rhizomatous means, forming dense carpets along the forest floor and blanketing it like Astroturf. These monocultures inhibit growing space and take up resources from native grasses, forbs, shrubs, and tree seedlings. Plant-munching deer also clear the forest floor of native plants, giving wavyleaf the chance to take over even more territory.
- It’s a recent addition to the ecosystem, so nothing has evolved to eat it, and no animals or insects have developed a taste for it. Its gooey seeds also make areas where it’s present unsuitable habitat for smaller woodland wildlife. Picture acres of forest understory carpeted with a plant nothing will eat and few animals can live in.
- The sticky seeds attach to anything and everything passing by: pets and wildlife, pant legs and shoes, bike and car tires. It’s able to spread easily and widely as a hitchhiker. Just one dog passing through the grass for only half a minute can end up covered in more than 2000 seeds.
A stroll through wavyleaf turns to woe | Photos: Vanessa Beauchamp, Towson University
Non-native invasive plants are everywhere already. Why should I care about wavyleaf specifically?
Compared to other NNIs, wavyleaf hasn’t been in the U.S. that long. It’s still in its early stages of establishment, so there’s a chance to contain it before it becomes as widespread as siltgrass and other invasive plants. Early Detection and Rapid Response (EDRR) is key!
When prevention fails, EDRR is the next line of defense against the establishment of invasive plants. EDRR increases the likelihood that small invasive populations will be found, contained, and eradicated before they become widely established. By educating the public about wavyleaf and documenting its location and abundance, park managers have an opportunity to take action early, which can slow wavyleaf’s range expansion and avoid the need for costly long-term control effots.
How can I help?
- Learn to recognize this grass and help other people learn it. Education is the most important tool!
- Remove it from your property. It has weak roots and can easily be pulled out by hand (prior to seed-set). After you pull the plants up, let them dry out so they don’t re-root.
- DO NOT walk through patches of the grass during the fall. The small seeds are very sticky, and you or your pet can pick them up and carry them with you to new areas.
- If you or your pet walk through wavyleaf while it’s in seed, try to remove the seeds before leaving the site. They can be removed from clothing and other gear with duct tape.
- Report infestations to the national mapping project through the Early Detection and Distribution Mapping System (EDDMapS) online or through the mobile application MAEDN.
- If you find it on park land in Baltimore City, please also report it to BCRP Forestry Division at firstname.lastname@example.org or (410) 207-4305.
By Taylor Brann, Invasive Vegetation Management