A new invasive weed species has been identified in Carlsbad and other parts of San Diego County. Ward’s Weed is a small compact plant in the mustard family that almost looks like a tiny tumbleweed. It is easy to identify by its small yellow flowers with four petals and unique beaked seed pod.

Ward’s Weed can grow as a thick mat that chokes out all other surrounding plant species. Due to the extremely high seed count of up to 30,000 seeds per plant per year, this species can spread quickly and also presents a fire hazard in our open spaces and canyons.

The species is new to North America, but its current infestation is in a small enough geographic area that it is possible to eradicate before it gets out of control. Similar to the tumbleweed or Sahara mustard, which have spread throughout the western U.S., Ward’s Weed can do the same if not eliminated. In Australia, it was determined that a single introduction in 1915 eventually spread throughout the continent. 

Ward’s Weed has been spotted in the City of Carlsbad. Learn how to spot it and report it at the  City of Carlsbad’s page on Ward’s Weed info page.  If you think you have spotted it, please report it via iNaturalist via the website or the app.

photos of Ward's Weed

Images of Ward’s Weed

Categories: Rose Creek


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