Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

Home to the plants of the Sonoran, Chihuahuan and Mojave Deserts

Cirsium ochrocentrum, Yellowspine Thistle

Oncosiphon piluliferum, Stinknet

Stinknet has pretty showy yellow or gold colored flowers. The showy flowers attracts a lot of positive attention however this species is an aggressive weed and spreads quickly through and disrupting native plant communities. Oncosiphon piluliferum Stinknet is an introduced species in Arizona and the southwestern United States causing much alarm from environmental groups that recognize how quickly this species can destroy yards and natural areas. Oncosiphon piluliferum Oncosiphon piluliferum, Globe Chamomile, Southwest Desert Flora    Stinknet, or Globe Chamomile as it is erroneously called has pretty rounded yellow flowers that unfortunately result in many folks wanting to bring it home as a garden species. You should resist any temptation to encourage this aggressive habitat destroying species. Oncosiphon piluliferum Stinknet leaves are bright green, alternate along the stems and pinnatifid with 3 to 5 linear lobes. Plants are bushy and often attractive in appearance. Oncosiphon piluliferum    Stinknet; shown in the photo growing in a natural area, side by side with another major invasive species, Buffalograss, Buchloe dactyloides. Oncosiphon piluliferum

Scientific Name: Oncosiphon piluliferum
Common Name: Stinknet

Also called:

Family: Asteraceae, Sunflower Family

Synonyms: (Cotula pilulifera, Matricaria globifera, Matricaria discoidea, Pentzia globifera)

Status: Introduced

Duration: Annual

Size: Up to 2 feet (60 cm) or more.

Growth Form: Forb/herb pungently scented; multiple green stems, glandular, branching, bushy.

Leaves: Green; alternate, dissected, leafy, pinnatifid with linear lobes, 3 to 5 lobes, lower leaves longer, upper leaves bract-like.

Flower Color: Yellow or Gold; flower heads solitary or in small clusters; disk flowers only; leafless flowering stalks (inflorescence); fruit is cypsela.

Flowering Season: March to June, dependent on rainfall.

Elevation: Sea Level to 3,000 feet (900 m); below 1,600 feet (500 m) in California.

Habitat Preferences: Lower desert areas in clay, sandy and gravelly soils and washes, often in disturbed areas; coastal scrub, dunes and chaparral vegetation in California.

Recorded Range: Central Arizona and moving to the north and south. In California in the Los Angeles area with confirmed records south of San Diego. This species was first recorded as an invasive in California.

North America & US County Distribution Map for Oncosiphon piluliferum.

Invasive/Noxious Weed Information: No data available.
Threatened/Endangered Information: No data available.

U.S. Weed Information: In Arizona, Oncosiphon piluliferum is a Class B, Noxious Weed under R3-4-245. Noxious Weeds; Noxious weeds are species that are known to occur, but of limited distribution in the State and may be a high priority pest for quarantine, control or mitigation if a significant threat to a crop, commodity, or habitat is known to exist."

Wetland Indicator: In North America Oncosiphon piluliferum has the following wetland designations: Arid West, FACU and Western Mountains, Valleys, and Coast, FACU
FACU = Facultative Upland, usually occur in non-wetlands, but may occur in wetlands

Genus Information: 2 species in Oncosiphon in the United States, both introduced. 1 species in Arizona.

The genus Oncosiphon was published by Mari Källersjö in 1988.

Comments: Stinknet is an introduced species found in central Arizona and southeast California. It was brought to Phoenix as a cultured desert habitat specimen. It is a fast moving invasive in Arizona quickly moving through the greater Phoenix area. At this time it is not listed as an invasive or noxious weed by Arizona or the federal government.

Stinknet is so named because it has a strong unpleasant odor.

Importance to Wildlife, Birds and Livestock
Birds may likely feed on the seeds of Oncosiphon piluliferum.

Special Value to Native Bees, Butterflies and Insects
Stinknet is likely visited by Native bees and other insects.

The genus Oncosiphon (Oncosi'phon:) is from the Greek "onkos" meaning "bulb and mass" and "siphon" meaning "tube"; referencing the tube of the corolla.

The genus Oncosiphon was published by Mari Källersjö in 1988.

The species epithet "piluliferum" (pilulif'erum:) means bearing little balls of globules, which here refers to the globular flowering heads.

Date Profile Completed: 06/26/2012, updated 03/19/2020
U.S. Dept. of Agriculture, Natural Resources Conservation Service on-line database
David J. Keil, FNA | Family List | FNA Vol. 19, 20 and 21 | Asteraceae | Oncosiphon, Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford.
FNA 2006, Jepson 2012 Editor; L. Crumbacher 2012, ; from SEINet Field Guide, on-line; - (accessed 03/19/2020).
David J. Keil 2012, Oncosiphon pilulifer, in Jepson Flora Project (eds.) Jepson eFlora, /eflora/eflora_display.php?tid=103818, accessed on March 19, 2020.
California Invasive Plant Council, Cal-IPC; accessed on March 19, 2020.
SEINet for synonyms, scientific names and recorded geographic locations,
Etymology:Michael L. Charters California Plant Names: Latin and Greek Meanings and Derivations; A Dictionary of Botanical and Biographical Etymology - (accessed 02/03/2020)