Yellow Starthistle

Yellow starthistle is an invasive Eurasian winter annual with yellow flower heads surrounded by sharp spines. [UC Statewide IPM](https://ipm.ucanr.edu/home-and-landscape/yellow-starthistle/) describes its identification and weed-management context. The Yavapai source's form code is P (perennial), but the identified species is annual; this record retains the correct annual type rather than copying the source's life-cycle error. Follow local invasive-plant and fuel-management guidance. ## Yavapai County — 2025 source The [University of Arizona Yavapai County bulletin](https://extension.arizona.edu/sites/default/files/2025-03/FirewisePlants3-14-2025.pdf), page 3, lists Star Thistle with the botanical entry Centaurea solstitialis and form P. It places this row in its fire-prone list. The bulletin says fire-prone plants can ignite readily and burn intensely, and should be removed or aggressively maintained if near a home, road or driveway. For native trees, page 3 calls for removing dead material, keeping limbs out of the lower 6–10 feet and clearing shrubs beneath the canopy. For other fire-prone native plants, it calls for isolated stands more than 30 feet from structures. Apply current local requirements and care suited to the plant. No plant is fireproof. This source classification is regional and must remain separate from ratings published elsewhere.