- Centaurea calcitrapa is a biennial to perennial plant. It grows 2-3 ft. (0.61-0.91 m) tall.
- The stems and leaves are covered with fine hairs. Lower and basal leaves are divided or deeply lobed. Leaves become less divided toward the apex of the plant.
- Flowering occurs from July to October, when purple to pink blooms develop at the ends of the stems. Floral bracts are tipped with 1 in. (2.5 cm) long, straw colored spines.
- The fruit is an achene 0.08-0.16 in. (2-4 mm) long which lacks a pappus.
- Ecological Threat
- A native of southern Europe, Centaurea calcitrapa produces prolific seeds and often invades floodplains, dry forests and grasslands.
- Oregon Department of Agriculture Plant Programs, Noxious Weed Control
- Washington State Noxious Weed Control Board
- University of California, Jepson Flora Project
- Flora of North America, www.eFloras.org
- Nevada Department of Agriculture
- California Invasive Plant Council
- USDA NRCS PLANTS
- USDA ARS GRIN