Dyer's Woad (Isatis tinctoria)

 
 
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Description
A winter annual, biennial, or a short lived perennial. The thick tap roots can be 3-6 meters in depth. The leaves are simple blueish-green covered with fine hair. The vein on the upper part of the leaf blade is creamy white. The stems range from 30-120 cm tall usually has 1 main stem that is simple below and branched above. The stem leaves are spear shaped and embraced by the stem. Flowers have a flat top with yellow petals. These can be found in terminal groups at the branch/stem end. The pear shaped fruit is a single seed closed in a flattened green pod. Sooner or later it will turn a black or a dark purplish brown color that is used to identify this weed after flowering.

Key Identifiers
  • Ranges from 30-120 cm tall
  • Numerous flowers that are yellow and very small
  • Basal leaves are oval and have stem, stem leaves appear to be clasping stem
  • Seed pods turn dark purple to black
Location in Canada
Located in British Columbia., Newfoundland, Ontario and Quebec. Isolated plants are suspected to be in Alberta.

Resources
California Department of Food and Agriculture - Dyer's Woad
USDA Forest Service, Fire Effects Information System - Dyer's Woad

Similar species
Dyer’s woad can be sometimes confused with other members in the Mustard family but it is distinguished by its unique pear shaped fruits.

Steve Dewey, Utah State University, Bugwood.org

Steve Dewey, Utah State University, Bugwood.org

Steve Dewey, Utah State University, Bugwood.org

 
 
 
 

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For more information about the content of this document, contact Nicole Kimmel.
This document is maintained by Shelley Barkley.
This information published to the web on April 10, 2012.
Last Reviewed/Revised on March 21, 2014.