Pyrethrum refers to several Old World plants of the genus Chrysanthemum (e.g., C. coccineum) which are cultivated as ornamentals for their showy flower heads. It is also the name of a natural insecticide made from the dried flower heads of C. cinerariifolium and C. coccineum. Some members of Chrysanthemum, including these two, are placed in another genus, Tanacetum, by some authorities. Both genera are members of the daisy (or aster) family, Asteraceae. They are perennial plants with a daisy-like appearance and white petals.