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Japanese chaff flower

(Achyranthes japonica)

Photo of Japanese chaff flower
Photo credit: Chris Evans, Illinois Wildlife Action Plan, Bugwood.org

Herbaceous perennial with opposite leaves, growing up to 1-2 meters tall. Fruits lay flat against elongated spikes that have a pair of stiff bracts. Seeds easily hitch a ride on clothing, shoes, and animal fur.

Overview

Other names for this plant include:
  • Common names: Japonica
  • Scientific names: Achyranthes bidentata var. japonica
Ecological threat:
  • Thrives in partial sun and moist soils, but also tolerant of a variety of conditions such as deep shade and dry soils.
  • It invades forests, riparian areas, open grasslands, and disturbed areas such as ditches and field edges.
  • It can produce thousands of seeds per square meter with nearly 100% viability and rapid germination.
  • Forms dense colonies (documented at over 70 plants per square meter), out-competing native herbaceous plants and reducing overall forest regeneration.
  • Seeds are easily spread by human activity.
 Overview map of prohibited classification in WI
Prohibited (red) counties

Classification in Wisconsin: Prohibited

Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. The recommendation for Japanese chaff flower was based upon this literature review [PDF] developed by the department.

Identification

Leaves & stems: Simple, opposite, ovate-elliptic shaped. Leaf margins are entire and slightly wavy. Somewhat resembles common pigweed with the venation of dogwood. The entire plant is slightly pubescent (covered in tiny, soft hairs).

Flowers: Flowers occur on tight clusters of erect spikes, blooming in late summer. Tiny flowers lack petals. The flowers form right angles from the spike, giving them a "bottle-brush" appearance. Flowering occurs in late summer.

Fruits & seeds: Fruits lay flat against elongated spikes that have a pair of stiff bracts that aid in attachment to clothes, shoes, and animal fur. Seed maturation occurs in early fall. As plants senesce and leaves die back, the stems and fruit remain erect into winter.

Roots: Vigorous root systems give rise to multiple stems.

Similar species: Japanese chaff flower resembles American lop seed (Phryma leptostachya; native), a common perennial forb of Wisconsin, especially when in fruit. American lop-seed can be best distinguished from Japanese chaff flower by its toothed leaves that come to an elongated point at the tip.

Distribution

Currently, there have been no reports of Japanese chaff flower in Wisconsin. Have you seen it? Send us a report.

Control

Mechanical:
  • Manual control is most effective for small infestations or newly germinated plants.
  • Because of the extremely vigorous root systems in established populations, continual monitoring of regrowth is needed after hand pulling mature plants.
  • Be sure to remove plants before the seed-set.
Chemical:
  • Herbicide treatments may need to be conducted about every two weeks to control plants as they germinate.
  • Effective control can be had with foliar applications of glyphosate or triclopyr at a 2% rate.
  • Control activities should be conducted before or at the onset of flowering. Herbicide applications conducted after seed production began were found to have decreased effectiveness.
  • River-to-River Cooperative Weed Management Area in southern Illinois is currently conducting tests of Garlon3A, Rodeo, and 2, 4-D at the 2% rate.

Photos

View Japanese Chaff Flower pictures in our photo gallery!

Resources

Sources for content:
  • USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network - (GRIN) [Online Database]. National Germplasm Resources Laboratory, Beltsville, Maryland.
  • River to River Cooperative Weed Management Area; Christopher Evans, September 2010
  • Wildland Weeds Newsletter; Christopher Evans, River to River Cooperative Weed Management Area and David Taylor, Daniel Boone National Forest. Summer/Fall 2011.
  • Japanese Chaff Flower Summit 2011 – Falls of the Ohio State Park, IN; History and Identification of Japanese Chaff Flower (Achyranthes japonica), Notes from the Discussion on Control.
Links for more information: