Stinknet

Oncosiphon pilulifer

Characteristics of stinknet:

  • Bright yellow globe-shaped flowers that turn tan when dry.

  • Flower heads are roughly the size of a pencil eraser.

  • No ray pedals like other types of sunflowers.

  • Pungent turpentine-like smell when crushed.

  • Only grows during the winter/spring.

  • May have a single or multiple stems.

  • Can grow into a 2-3 ft shrubby shape.

  • Can grow as small as a centimeter.

  • Bright green carrot-like leaves.

Stinknet seeds can germinate multiple times throughout the growing season. Green and dried plants can be present at the same time.

Why is it a hazardous species?

  • Causes headaches, respiratory, and/or skin reactions in some people.

  • Dried plants can spread wildfire and produce caustic smoke.

  • It outcompetes and displaces native wildflowers.

  • Degrades rangelands and natural landscapes.

  • Livestock can get sick if too much is eaten. Can cause bloat or colic.

  • It has no natural predators in the U.S.

  • Wildlife will avoid eating it.

  • It spreads rapidly and exponentially.

How did it get here?

  • Native to South Africa.

  • Introduced accidentally to San Diego in the 1980s from increased global travel.

  • Spread to southern Arizona on vehicle tires along the interstate corridors by the 2010s.

Stinknet leaves look like succulent carrot leaves.

Stinknet belongs to the sunflower family. Dried plants are a fire hazard.

Want to learn more?

Each stinknet plant can produce hundreds or thousands of seeds.