Achyranthes japonica (Miq.) Nakai
Japanese Chaff Flower
Family - Amaranthaceae
Habit - Perennial forb with thickened roots.
Stems - Erect, to about 1.5 m, glabrous or pubescent.
Leaves - Opposite, on petioles to 3.5 cm. Blades elliptic, to 13 x 7 cm, acute to acuminate, entire, pubescent on top surface and on veins beneath. Venation is arching, in a manner similar to Cornus
Inflorescence - Terminal and axillary spikes, initially dense, elongating and opening up later, to 20 cm, greenish. Toward maturity, fruits become reflexed to inflorescence axis.
Flowering - August - September.
Habitat - Bottomlands along major rivers.
Origin - Native to Asia.
Other info. - Chaff flower is an invasive weed first reported in North America from eastern Kentucky in the early 1980s. Since then it has been spreading down the Ohio River and into the Mississippi. The plant does not tolerate annual flooding, so where occurring in bottomlands it is usually found on the first terrace above the annually flooded zone. It can be inadvertently spread by mowers, agricultural equipment, and clothing and footwear. It is considered a high priority invasive in some areas, and confirmed populations should be eradicated when possible.
Photographs taken in Mississippi County, MO, near Mississippi River,about 8 mi south of confluence with Ohio River, 8-29-2011 (SRTurner).