Santa Maria feverfew: Full Sun Plant

What Is Santa Maria feverfew and Where Does It Come From?

Santa Maria feverfew (Parthenium hysterophorus) is an annual herb in the daisy family (Asteraceae), native to the Americas, with its center of origin in northeastern Mexico. It grows upright with a deep taproot, reaching 1.5 m, or sometimes 2 m in fertile soil. It begins as a ground-level rosette before bolting and branching into a shrub-like form. The leaves are light green, deeply lobed, resembling carrot leaves, and covered with soft hairs. The flowers are small white or cream heads, 4 to 10 mm in diameter, produced in large quantities at the branch tips, each containing small black seeds. It is considered one of the ten most aggressive weeds in the world and has spread to approximately 40 countries. In Brazil, it appears mainly in São Paulo and Paraná, in vacant lots, roadsides, degraded pastures, coffee plantations, and vineyards. The plant contains parthenin, a substance that causes contact dermatitis, allergic reactions, and asthma attacks in sensitive individuals, and is toxic to livestock.