Centaurea solstitialis is an annual herb from the family Asteraceae. During the vegetative stage it forms a rosette of non-spiny leaves, between 5–20 centimetres (2–8 inches) in diameter. As the summer approaches, it produces a flowering stem up to 1 metre (3+1⁄2 feet) in height. The leaves at the base are lobed and range between 5–8 cm (2–3 in) in length, while the ones on the stem are unlobed and smaller. Between May and October, the stem produces numerous spinous flower heads (capitula) about 12–16 millimetres (1⁄2–5⁄8 in) across, containing between 10–50 yellow flowers, with spines between 1–2.5 cm (3⁄8–1 in). Flowers within capitula are pollinated by insects and each capitula produces 10–50 seeds, some with and some without a pappus. It is an annual semelparous species, and will die after reproduction is completed, normally by the end of the summer.
