• Home
  • How We Work
  • Where We Work
  • News Room
  • About Us
  • My Nature Page

Conservation Science

Conservation Strategy - Conservation by Design

Conservation Methods

Partners of The Nature Conservancy

Conservation Initiatives

The Nature Conservancy in Africa - Conservation in Africa

The Nature Conservancy in Asia Pacific - Conservation in Asia-Pacific

The Nature Conservancy in the Caribbean - Conservation in the Caribbean

The Nature Conservancy in Central America - Conservation in Central America

The Nature Conservancy in North America - Conservation in North America

The Nature Conservancy in the United States - Conservation in the United States

The Nature Conservancy in South America - Conservation in South America

Japanese Knotweed - Polygonum cuspidatum

knotweed
Japanese Knotweed©Plant Conservation Alliance

Japanese knotweed is on the worst pest list for the The Nature Conservancy's North Carolina mountain region.

Japanese knotweed tolerates a variety of adverse conditions including full shade, high temperatures, high salinity, and drought. It spreads quickly to form dense thickets that exclude native vegetation and greatly alter natural ecosystems.It is found near water sources, such as along streams and rivers, in low-lying areas, waste places, utility rights-of-way, and around old homesites. It poses a significant threat to riparian areas, where it can survive severe floods and is able to rapidly colonize scoured shores. Once established, populations are extremely persistent.

Japanese knotweed is an upright, shrublike, herbaceous perennial that can grow 10 feet tall. Stems of Japanese knotweed are smooth, stout and swollen at joints where the leaf meets the stem. The base of the stem at each joint is surrounded by a membranous sheath. Leaves may vary in size, but are usually about 6 inches long by 3 to 4 inches wide, broadly oval to somewhat triangular and pointed at the tip. The minute greenish-white flowers occur in attractive, branched sprays in summer and are followed soon after by small winged fruits. Seeds are triangular, shiny, and very small, about 1/10 inch long.

Japanese knotweed spreads primarily through rhizomes and is often introduced as a contaminant in fill dirt. Seeds are distributed by water and wind.