Madagascar Purple Flower

"Ageratum houstonianum" syn. "Ageratum mexicanum" Hort. 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 flowers. The flower heads are borne in dense corymbs. The ray flowers are threadlike, leading to the common name.