Weed of the Season:
“We abuse land because we regard it as a commodity belonging to us. When we see land as a community to which we belong, we may begin to use it with love and respect.”
Japanese stiltgrass carpeting parkland in fall | Photo: Chris Evans, University of Illinois
Fall is a particularly challenging time for NNI management since so many of our pest plants are preparing to disperse their seeds. Our Weed of the Season, Japanese stiltgrass – is a fine example. Introduced to the United States in 1919, the grass likely escaped shipping crates containing it as packing material to protect porcelain goods from Asia. Japanese stiltgrass readily propagates in a variety of biomes and sunlight conditions, highlighting our level of concern for its rapid, carpet-like spread.
Active management of Japanese stiltgrass is not advised at this time of year since it is already spreading seed. What we can do this fall is put on our citizen scientist hats to observe an infested area, take photographs with detailed notes, and practice plant identification! A little plug here for the MAEDN (Mid-Atlantic Early Detection Network) smart phone app– as it is our favorite resource to collect and share NNI management data. If you do not have access to a smart phone/tablet, you may send your detailed notes to firstname.lastname@example.org.
Let’s get out our hand-lenses folks! Though extremely difficult to safely move NNI plants with seeds, the prominence of a seed head on grass is incredibly helpful for plant identification purposes. Our Weed of the Season is distinguished by its small, wiry bamboo-like appearance and can grow to 3 feet tall. It boasts a shiny, hair-lined midrib down its ~3 inch long, pale green, asymmetrical lanceolate leaves. Other notable characteristics are the slender stalks of tiny paired flowers late in summer (August through September-early October) which transform into dry yellow/red fruit achenes shortly thereafter. Japanese stiltgrass has a sprawling habit that displaces less competitive native species by forming extensive patches. The plant will root from stem nodes that touch the ground to facilitate spread, but the shallow roots are easily pulled. Seed germination will begin a few weeks before crabgrass emerges in early spring- a worthwhile time to return for further observations and management. By familiarizing ourselves with multiple characteristics of individual species, we are better able to approach management with confidence.
A few key points come to mind while considering nonnative invasive (NNI) plant management in our urban landscape: (1) plant identification, (2) habitat sensitivity, and (3) disposal methods. By familiarizing ourselves with these points we can be the most responsible of land stewards. So please remember:
1. If you come upon a familiar invasive plant but one or a few characteristics look off, use all of your identification tools to confirm you’re not dealing with a native look-alike. For instance, Japanese stiltgrass has several look-alike species: Virginia cutgrass (Leersia virginica) and Hairy jointgrass (Arthraxon hispidus), amongst others.
2. We must consider the different impacts of various plant removal techniques, particularly in sloping areas. Removing plants with deep root structures may loosen the soil and promote destructive erosion.
3. If seeds or seed pods are present, use extreme caution to avoid incidental spread. In lightly infested areas you may opt to remove individual seed heads from plants, but these seeds must be sterilized or sent to the landfill in secured plastic bags. Otherwise, make note of the infested area and plan a spring removal event.
Encroaching stiltgrass in Gwynns Falls/Leakin Park; NNI management on slopes (right) should be approached with extreme caution | Photo: Biohabitats, fall 2016
I hope you enjoy your fall plant ID practice and participation in Baltimore’s urban forest management goals. Thank you graciously for getting out there. Happy hunting!
-Ashley Dickerson, Environmental Conservation & Education Coordinator