Basic info - Japanese chaff flower is a perennial plant that can grow to heights of 2.5 to 5 feet [1,2]. It tends to prefer wooded riverbank habitats, though it can grow just about anywhere. As its name might suggest, it is native to Japan, as well as other various portions of Asia. How this species arrived in the US seems to be unclear, but it was first detected here in the early 1980's.
Impacts - This plant can grow in dense stands, crowding and shading out native plants, which in turn damages habitat for wildlife and can even negatively impact water quality. The fruit of the chaff flower is covered with stiff little hairs (bracts) which easily stick to clothing and fur, aiding in its dispersal to new locations. Its preferred habitat near waterways also contributes to its dispersal as its seeds are carried to new areas by the currents.
Identification - The Japanese chaff flower can be difficult to identify until it flowers, as its leaves look very similar to a number of other plants, especially young dogwood trees. Its green stems can reach heights of 3 to 6 feet tall, with juvenile plants having red stems. Its leaves are green, oval-shaped, and around 5 inches long at maximum. Its distinctive flower spikes are about an inch and a half long, elongating to 8 inches when it fruits.
What can you do to help? - If you've identified a Japanese Chaff flower, or think you might have but aren't sure, you can report your discovery on the EDDMapS (Early Detection and Distribution Mapping System) app or website, or upload an image of it to the iNaturalist app.
While some smaller, younger plants can be pulled by hand, the Japanese chaff flower tends to have massive, ingrained root systems that make manual removal overly difficult to impossible. Mowing can prevent flowering, but often will not kill the plant once established, and can inadvertently spread the seeds if not done before the plants bloom. All removed plants and plant parts should be placed in plastic bags to be disposed of. Never compost invasive plants.
In the case of the Japanese chaff flower, it seems that herbicidal solutions work best to manage large and/or well established plants and stands.
Written by: Clover McDougall
Banner photo by James Kamstra via ontarionature.org