UC IPM Online UC ANR home page UC IPM home page

UC IPM Home

Search

SKIP navigation

Home & garden
Agriculture
Natural environments
Exotic & invasive

Weather data & products
Degree-days
Interactive tools & models

Publications & more
Workshops and events
PCA exam helper
Pesticide information

Grants programs
Funded-project results


 

How to Manage Pests

Identification: Weed Photo Gallery

Common knotweed (prostrate knotweed)

Scientific name: Polygonum arenastrum (Family Polygonaceae)

Life stages of Common knotweed (prostrate knotweed) top left picture top right picture bottom left picture bottom right picture

Click on image to enlarge

DESCRIPTION:
Common knotweed (prostrate knotweed) is a summer annual weed which can thrive even on poor and compacted soil. The seed leaves are long, very narrow, rounded at the tip and light green with a white cast. The true leaves are much broader, emerging from an encircling, membranous sheath at the leaf base. The mature plant grows prostrate to erect with slender, tough stems, which are extensively branched, giving it a zigzag appearance. The tiny, green flowers with white or pink margins sit in clusters of 2 to 5 on short stalks in leaf axils.

See UC IPM's Common Knotweed Pest Note for more information.

Broadleaf ID illustration.


Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2008 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See How to manage pests, or in the U.S., contact your local Cooperative Extension office for assistance. /PMG/WEEDS/common_knotweed.html revised: March 11, 2008. Contact webmaster.