Common names: Yellow Starthistle
Description: Member of the sunflower family. 18-36 inches tall.
Flowers: Yellow flowers with 3/8-3/4 inch spines in star-like arrangements at the base of the flower heads.
Leaves: Dull green color, covered with fine, wooly hairs. A basal rossette of leaves occurs at the base of the stem, which are pinnately lobed with the distal portion more rounded and larger.
Reproduction: The marginal flowers produce nonplumed seeds and the central flowers plumed seeds. This allows the plant to spread easily by wind or land. It is now widely spread through contaminated commercial seed.
Flowering: Mid July to early August.
Habitat and Ecology: Introduced from the Meditteranean. May poison horses or damage cattle with spines. Highly invasive throughout California and Pacific Northwest.'