California Invasive Plant Council

Parthenium hysterophorus

Common names: Santa Maria feverfew

Parthenium hysterophorus (Santa Maria feverfew) is a herb (family Asteraceae) with white flowers and lobed leaves found in the south coast ranges of California. It is native to the American tropics. It favors grasslands and riparian and bottomland habitat. It is a prolific seed producer. Its seeds travel via wind, water, birds, vehicles, farm machinery and other animal traffic.

Cal-IPC Rating: Watch

CDFA Rating: A*?

Explanation of CDFA ratings

• A – A pest of known economic or environmental detriment and is either not known to be established in California or it is present in a limited distribution that allows for the possibility of eradication or successful containment.
• B – A pest of known economic or environmental detriment and, if present in California, it is of limited distribution.
• C – A pest of known economic or environmental detriment and, if present in California, it is usually widespread.
• D – An organism known to be of little or no economic or environmental detriment, to have an extremely low likelihood of weediness, or is known to be a parasite or predator.
• * – An asterisk next to the rating indicates that a plant is included in the CCR Section 4500 list of California State Noxious Weeds.

More details

Assessment(s)

Plant Risk Assessment - An evaluation of the potential for a plant to be invasive in California.

Weed Management Notes

Cal-IPC Newsletter Articles

• CDFA expands noxious weed list and revises process. Kelch, Dean. Vol 23, Issue 2

Cal-IPC Symposium Presentations

Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.

• Successes, failures, and lessons from the Orange County CNPS Emergent Invasive Program. Vanderhoff, Ron (2019)
• New and expanding weeds in California. Kelch, Dean (2011)

Other Parthenium hysterophorus Information

• CalPhotos - Images of plants taken mostly in California.
• Calflora - Distribution map and records of this species in California.
• CalWeedMapper - Distribution map of this species in California with ability to determine regional priorities.
• EDDMapS - Distribution of this species in North America.
• USDA PLANTS Database - Information on identification and distribution, with links to websites in individual states.