Oncosiphon pilulifer
Stinknet
(c) Perry Grissom, some rights reserved (CC BY) · licence
Family: Asteraceae · Type: Herb · Not Native
Conservation status: Cal-IPC Yes
Oncosiphon pilulifer (Stinknet) is a non-native California herb in the Asteraceae family, recognized by Recent introduction from South Africa, rapidly expanding range.
Stinknet is a naturalized annual found in southern California coastal regions, including San Diego and the Peninsular Ranges, in disturbed sites, coastal scrub, and chaparral at elevations below 500 meters. Flowering from March to July, this plant produces small, spherical yellow-green flower heads approximately 5 to 8 millimeters in diameter. Growing with branched stems 15 to 45 centimeters tall, often reaching up to 70 centimeters, with a distinctively pungent scent. Its leaves are 1 to 4 centimeters long, covered in fine, short hairs and spread throughout the plant's branching structure. The tiny flowers have pale corollas measuring 1.5 to 2 millimeters long, with fruits measuring just 0.6 to 0.8 millimeters at maturity.
Identification and appearance
Key characters: Recent introduction from South Africa, rapidly expanding range
Habitat and range
Habitat: Disturbed sites; coastal scrub, chaparral
Elevation: < 500 m
Outside California: Arizona, native to South Africa, alien in Australia
Bloom period
Oncosiphon pilulifer blooms Mar-Jul.
Conservation status
Cal-IPC Yes
How to tell it apart
vs Matricaria: Oncosiphon smells intensely foul and has spherical heads; Matricaria smells sweet (apple-like) and has egg-shaped heads.; vs Cotula: Oncosiphon has intensely pungent odor and spherical heads; Cotula lacks strong odor and has button-like flattened heads.; vs Helenium: Oncosiphon has foul-smelling spherical heads; Helenium has no strong odor and ball-shaped yellow flower centers with drooping rays.; vs Eriophyllum: Oncosiphon smells foul with spherical heads; Eriophyllum has woolly gray foliage and daisy-like yellow flowers.; vs Acamptopappus: Oncosiphon is foul-smelling with ball-like heads; Acamptopappus is a woody shrub with flat-topped yellow flower clusters.
Frequently asked questions
Is Oncosiphon pilulifer native to California?
No. Oncosiphon pilulifer is not native to California (recorded as not native).
When does Oncosiphon pilulifer bloom?
Oncosiphon pilulifer blooms Mar-Jul.
What plant family does Oncosiphon pilulifer belong to?
Oncosiphon pilulifer is in the Asteraceae family, genus Oncosiphon.
Is Oncosiphon pilulifer invasive in California?
Oncosiphon pilulifer is listed by Cal-IPC with an invasiveness rating of Yes.
What habitat does Oncosiphon pilulifer grow in?
Oncosiphon pilulifer grows in Disturbed sites; coastal scrub, chaparral.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.