Polygonum sahalinensis (Fallopia sachalinensis)
*Detected in Michigan*
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Barbara Tokarska-Guzik, University of Silesia, Bugwood.org
- Perennial, herbaceous shrub that can grow over 12 feet high
- Hollow stalks are light green, smooth and swollen at the nodes, resembling bamboo
- Similar to Japanese knotweed, and the two plants may hybridize
- Flowers are arranged in spikes near the end of the stem are small, numerous, and greenish-white in color
- Flowers do not extend past the length of the leaves
- Flowers bloom in August and September in Michigan
- Giant knotweed leaves are 6-14 inches long, heart-shaped at the base and have fine hairs on the underside
Habitat: Giant knotweed can be found in moist soils in sunny areas along roadsides, disturbed fields or vacant lots and along streams or river banks.
Native Range: Japan
U.S. Distribution: Areas of the northeast and northwest United States. Locations in Michigan’s Upper and Northern Lower peninsulas
Local Concern: Giant knotweed spreads aggressively by roots (rhizomes) and cut or broken stems. It can form dense thickets along streambanks, actually increasing erosion potential and decreasing habitat value.