Ageratum houstonianum (flossflower, bluemink, blueweed, pussy foot, Mexican paintbrush) is a cool-season annual plant often grown as bedding in gardens. The plant grows to 0.3–1 m high, with ovate to triangular leaves 2–7 cm long, and blue flowerheads (sometimes white, pink, or purple). The flower heads are borne in dense corymbs. The ray flowers are threadlike, leading to the common name. The plant is native to Central America and adjacent parts of Mexico, but has become an invasive weed in other areas.