Tansy Ragwort is a poisonous Eurasian weed that can cause llivestock deaths. It is found in grassland, distrubed sites, and along roadways.

An undistrubed plant has a stout, erect, or slightly spreading stem. Tansy Ragwort begins its first year as a seedling with smooth uniform leaves.
The leaf stalks and stem are often purplish. From late June onward, one or more leafy stems elongate to bear flowers. At maturity, flowering stems are 2 to 4 feet tall and branched toward the top. They bear flat-topped clusters of yellow-petalled, daisylike heads that bloom mid-July through mid-October.
Tansy is prevalent throughout Clatsop County in open fields, along roadsides, and in areas of ground disturbance.
 

For more information on Tansy Ragwort and other weeds, please visit the following Web sites:

California Dept. of Agriculture
http://pi.cdfa.ca.gov/weedinfo

USDA Home page for all plants. Click on "invasive and noxious" or use Search feature
http://plants.usda.gov

Animal & Plant Health Inspection Service _ Noxious Weed Home page
http://www.aphis.usda.gov/ppq/weeds/

Wildlife Invasive Species Team/Nature Conservancy
http://tncweeds.ucdavis.edu/esadocs.html