Rainfarn

<em>Tanacetum vulgare</em>, common tansy, is a perennial herbaceous plant in the family Asteraceae, native to temperate regions of Asia and Europe and widely naturalized across North America, Australia, and South America. It typically grows in disturbed habitats, roadsides, riverbanks, and waste ground, forming dense colonies through vigorous rhizome spread. The plant bears deeply divided, fernlike leaves and clusters of bright yellow, button-like flower heads in late summer. It is classified as Least Concern on the IUCN Red List given its expansive, growing range. Common tansy contains toxic compounds including thujone and camphor, making it poisonous to livestock and humans in large quantities, though historically it was used as a culinary herb and medicinal plant. Its strong aromatic scent has traditionally been used as an insect repellent. The species is considered invasive in several regions outside its native range. It provides nectar and pollen for various insects. Biological traits such as precise seed output figures, individual lifespan, and biomass data remain poorly documented in standardized assessments.