Weeds Identification Gallery

Tarweeds

  • Hemizonia spp.
  • Sunflower Family: Asteraceae
Updated: 01/2026

Tarweeds, which include several species in the sunflower family, occur throughout California and are found in rangelands, pastures, and roadsides. All have sticky, heavily scented leaves. Shown here is three-rayed tarweed.

A small green seedling with slender leaves grows in sandy soil. Copyright information is at the bottom (Copyright 2007 The Regents of the University of California. All rights reserved.). Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources
Threerayed tarweed seedling. Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources

Mature Plant

Mature tarweeds range from about 1 to 1-1/2 feet (30–45 cm) high. Lower leaves are deeply lobed and lancelike. Upper leaves are flattened against the stem, glandular and hairy.

Flowers

The petals have three-toothed edges and may be yellow or white depending on the species and variable in number from three to many per flower.

closeup showing three yellow ray flowers with three-toothed edges; Monterey Co., 7/89 Credit: Jack Kelly Clark, UC IPM
Threerayed tarweed flower. Credit: Jack Kelly Clark, UC IPM
A bright yellow flower blooms on a spiky green plant against a blurred brown background. Copyright information is at the bottom (Copyright 2007 The Regents of the University of California. All rights reserved.). Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources
Flower of parry’s tarweed. Credit: Joseph M. DiTomaso, UC Agriculture and Natural Resources
Scattered seeds on a gray background, varying in color from light beige to dark brown, displaying different shapes and textures. A 1-millimeter scale indicates size and shows the seeds are 2 to 3 millimeters. Copyright information is at the bottom (Copyright 2007 The Regents of the University of California. All rights reserved.). Credit: James A. O'Brien, University of California
Fitch’s tarweed seed. Credit: James A. O'Brien, University of California
Eleven variously colored and textured seeds are arranged in a semi-circle on a plain gray background. Scale shows each seed is about 1 millimeter. Copyright information is at the bottom (Copyright 2007 The Regents of the University of California. All rights reserved.). Credit: James A. O'Brien, University of California
Parry’s tarweed seed. Credit: James A. O'Brien, University of California

More Information

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