California Invasive Plant Council

Oncosiphon pilulifer

Synonyms: Matricaria globifera, Pentzia globifera, Oncosiphon piluliferum

Common names: stinknet; globe chamomile

Oncosiphon pilulifer (stinknet) is a strongly-scented annual herb (family Asteraceae) with round yellow flowers and finely dissected leaves found in the south coast and desert ranges of Southern California. It is native to South Africa. It favors dunes and scrub and chaparral habitat. It spreads via seeds which travel through human activities and machinery.

Cal-IPC Rating: High?

Explanation of Cal-IPC ratings

• High – These species have severe ecological impacts on physical processes, plant and animal communities, and vegetation structure. Their reproductive biology and other attributes are conducive to moderate to high rates of dispersal and establishment. Most are widely distributed ecologically.
• Moderate – These species have substantial and apparent-but generally not severe-ecological impacts on physical processes, plant and animal communities, and vegetation structure. Their reproductive biology and other attributes are conducive to moderate to high rates of dispersal, though establishment is generally dependent upon ecological disturbance. Ecological amplitude and distribution may range from limited to widespread.
• Limited – These species are invasive but their ecological impacts are minor on a statewide level or there was not enough information to justify a higher score. Their reproductive biology and other attributes result in low to moderate rates of invasiveness. Ecological amplitude and distribution are generally limited, but these species may be locally persistent and problematic.
• Alert – An Alert is listed on species with High or Moderate impacts that have limited distribution in California, but may have the potential to spread much further.
• Watch – These species have been assessed as posing a high risk of becoming invasive in the future in California.

CDFA Rating: Q?

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.
• Q – An organism or disorder suspected to be of economic or environmental detriment, but whose status is uncertain because of incomplete identification or inadequate information.
• * – An asterisk next to the rating indicates that a plant is included in the CCR Section 4500 list of California State Noxious Weeds.
• -* – This plant is included in the CCR Section 4500 list of California State Noxious Weeds, but is otherwise not rated.

More details

Assessment(s)

Plant Assessment Form - Information gathered by Cal-IPC on the impacts, rate of spread, and distribution of invasive plants in California. Does not include management information.

Species ID Card

Invasive Species ID Card - To support field identification of early detection species, Cal-IPC has designed a set of Species ID cards that can be downloaded, printed double-sided, and trimmed to size.

Weed Management Notes

Cal-IPC Newsletter Articles

• Spotting rare weeds in Bay Area creeks. Mo, Jennifer. Vol 31, Issue 1
• Another stinkin' weed: Stinknet expands in southern California. McDonald, Christopher. Vol 27, Issue 1

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.

• Big Canyon Habitat Restoration and Resiliency Project Phase 3: CEQA exempt through CDFW’s SERP process. Arenas, Alys (2023)
• Developing a post-fire EDRR framework. Quon, Lauren; Fitch, Robert; Laskey, Hailey (2022)
• Early detection surveys in the Holy Fire burn area. England, Joy (2022)
• Prescribed burning may produce refugia for Oncosiphon piluliferum. Schwab, Stuart; Jenerette, G. Darrel; Larios, Loralee (2022)
• Regional EDRR with Bay Area WMAs. Johnson, Doug; Valentine, Nicole (2022)
• Seasonal herbicide management for invasive plant control: insights from stinknet. Rodriguez, Clarissa; McDonald, Christopher; Larios, Loralee (2022)
• The role of fire in managing invasive species at the Santa Rose Plateau Ecological Reserve. Laskey, Hailey; Principe, Zach (2022)
• Challenges managing the novel large-scale invasion of stinknet (Oncosiphon pilulifer) at the Santa Rosa Plateau Ecological Reserve. Laskey, Hailey; Principe, Zach (2021)
• Drone imagery and a simple spatial analysis technique for long-term mapping of stinknet (Oncosiphon pilulifer). Burson, Emily (2021)
• Lessons learned after nearly a decade of managing and monitoring stinknet (Oncosiphon pilulifer) across Southern California. McDonald, Chris (2021)
• Post-fire surveys for rare and invasive plants in the San Bernardino Mountains. Fraga, Naomi (2021)
• Arizona joins California in battling stinknet. Chamberland, Michael (2020)
• Assessing chemical management options for the control of stinknet (Oncosiphon piluliferum). Rodriguez, Clarissa; Bean, Travis; McDonald, Christopher; Larios, Loralee (2020)
• Some insights on the seed bank dynamics of stinknet, a difficult weed to contain. McDonald, Christopher; Douglas, Alex (2020)
• Adaptive management of stinknet (Oncosiphon piluliferum) in a coastal sage scrub preserve in North County, San Diego. Burson, Emily (2019)
• Do Oncosiphon piluliferum soil legacy effects post-removal inhibit restoration success? Schwab, Stuart (2019)
• Environmental factors and herbicide effect on germination rates of stinknet (Oncosiphon piluliferum), an invasive weed in Southern California. Perez-Ochoa, Zara; de la Rosa, Carlos A. (2019)
• Evaluating the efficiency of herbicides for management for Oncosiphon piluliferum (stinknet). Rodriguez, Clarissa; Bean, Travis; McDonald, Christopher; Larios, Loralee (2019)
• Weed Red Alerts. Kelch, Dean (2018)
• 2016 Weed Alerts. Kelch, Dean (2016)
• Weed Alerts 2010. DiTomaso, Joseph (2010)

Other Oncosiphon pilulifer Information

• CalPhotos - Images of plants taken mostly in California.
• Calflora - Distribution map and records of this species in California.
• EDDMapS - Distribution of this species in North America.
• GBIF - Global distribution information.
• Jepson Interchange - Information on this plant's taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
• USDA PLANTS Database - Information on identification and distribution, with links to websites in individual states.
• The Plant List - Global taxonomic resource and collaborative clearinghouse from Kew Gardens, the Royal Botanic Gardens, the Missouri Botanic Garden and others.

Additional photos