Yellow Starthistle – Centaurea solstitialis
Note: A similar but less noxious weed, Centaurea melitensis, is widespread throughout the area; this plant is characterized by smaller, more abundant spines around the flower head and is generally smaller in overall size.
Photo credits: Top: Justin Smith; Bottom Left-to-Right: none, Joe DiTomaso, Neal Kramer, none.
What does it look like?
Plant: Annual to short-lived perennial herb, ankle to shoulder height (usually 1 to 5 ft when in flower) and generally mounded with many branching stems - particularly when tall.Leaves: Gray-green, slightly downy (minute hairs on surface), alternate and either simple or partially lobed.
Flowers: Yellow; characterized by having sharp, rigid spines around flower heads. Generally blooms during the summer months. Only reproduces by seed.
