Chaff flower (Achyranthes japonica), also called Japanese chaff flower, is an invasive plant that is spreading fast. This perennial herbaceous plant grows densely, crowding out other plant species. It is easily introduced to new areas through seeds that move along waterways and stick onto fur and clothing. It is already a major problem in Kentucky, Ohio, Illinois, and Indiana and has been reported as far north as islands in Lake Erie.
Scientists and land managers are concerned about chaff flower because of the speed with which it takes over after it arrives in an area. It forms dense monocultures in sensitive riparian habitats which negatively impacts native plant diversity and regeneration as well as habitat for other species and water quality.
Download a chaff flower information sheet, available in English and Spanish.
Chaff flower is native to Asia. Its first detection in North America was in eastern Kentucky in the 1980s. Since then, it has rapidly spread, especially along the Ohio River, and more recently down the Mississippi River. There is also a large population in the Atlanta, Georgia area.
Chaff flower is not regulated as an invasive species or a noxious weed in Illinois.
Chaff flower is a habitat generalist, and it can grow nearly anywhere. While it prefers and has spread most rapidly along stream systems and bottomlands it also thrives in a wide range of other habitats including roadsides, ditches, field edges, and gardens. It prefers partial sun and moist soils, but it can also grow in shady or drier conditions.
This perennial herbaceous forb grows 3 to 5 feet tall. It has opposite leaves with smooth edges with very prominent, arching veins and pointed tips. The leaf color can vary, from reddish purple to bright green. The stems are squarish and nodes where leaves are attached are inflated and frequently have a reddish color. Individual flowers are small and green, not very distinctive, but occur in a distinctive bottlebrush spike. As flowers mature into seed this spike elongates with fruits (papery chaff over a single seed) held along stem. Two stiff hairs (bracts) on the backs of the fruits make them stick to clothes and fur. Leaves die back in fall, but stem (and the seeds on it) remain through winter turning a tan light brown color.
Chaff flower can be hard to distinguish from other plants until flowering, at which point the bottlebrush spike is distinctive. Venation on leaves of small plants can look almost like a young dogwood or basil plant. Other look-alikes include:
Managing chaff flower requires patience and persistence. Prevention is better than removal.
University of Illinois Extension Forester Chris Evans reviews how to identify Japanese chaff flower along with discussing its ecology, history in North America, and its current known distribution. This presentation was part of the 2021 Japanese Chaff Flower Summit, hosted by the University of...
Help track chaff flower and other invasive plants by reporting sightings through EDDMapS. Either download the app or report plants through the website.
Explore more about Chaff Flower through recorded presentations from the 2021 Japanese Chaff Flower Summit.
