Japanese knotweed (Polygonum cuspidatum)
Appearance: Shrub-like, arching perennial herbaceous plant, over 10' high, reddish-brown stems, smooth, stout hollow and swollen at the joint where the leaf meets the stem.
Leaves: Alternate broadly oval and pointed at the tip, about 6" long, 3 - 4" wide.
Flowers: Greenish-white, branched clusters which grow from leaf axils, near the end of stems, blooming in late summer.
Fruit: Small winged, carry triangular, shiny and very small seeds.
Roots: Long, stout horizontal stems growing below the soil surface, called rhizomes, forming roots and producing new plants allow the plant to spread vegetatively as well.
- Minnesota Department of Agriculture Information
- University of Minnesota Extension
- Biology, Ecology and Management of Knotweeds (Montana State University)
- Wisconsin DNR Japanese knotweed Brochure and Website
- Control information from Midwest Invasive Plant Network Control Database (search for Japanese knotweed and fill in other information for your situation)
- US Forest Service Fact Sheet
- Plant Conservation Alliance Fact Sheet
- MIPN Fact Sheet
- Homeowner's Guide to Japanese Knotweed Control (Northwoods CWMA)
- NRCS Management of Japanese knotweed