Verbena bonariensis (purpletop vervain, clustertop vervain, Argentinian vervain , tall verbena, or pretty verbena) is a member of the Verbenaceae family cultivated as a flowering annual or herbaceous perennial plant. In USA horticulture, it is also known by the ambiguous names "purpletop" (also used for the grass Tridens flavus) and "South American vervain" (which can mean any of the numerous species in the genus Verbena occurring in that continent). It is native to tropical South America where it grows throughout most of the warm regions, from Colombia and Brazil to Argentina and Chile.
Verbena bonariensis is a tall and slender-stemmed perennial. It can grow to 120 cm tall and can spread to 90 cm wide. At maturity, it will develop a woody base. Fragrant lavender to rose-purple flowers are in tight clusters located on terminal and axillary stems, blooming from mid-summer until Autumn frosts. The stem is square with very long internodes. Leaves are ovate to ovate-lanceolate with a toothed margin and grow up to 10 cm long.
V. bonariensis self-seeds readily. This ability has raised concerns that it may become an invasive species and noxious weed in favourable habitats. It has naturalised in a number of southern United States. Presently, the plant is on the invasive species watchlist for Washington state, naturalised in tropical and southern Africa, temperate Asia, Australia, New Zealand, the United States (including Hawaii), the West Indies, Macaronesia and the Mascarene Islands. According to Pacific Island Ecosystems at Risk, it is considered a weed in Fiji, New Guinea and other South Pacific islands.
Here it is growing as a weed by the Darebin Creek in Preston, in suburban Melbourne. It is very commonly encountered, but is not considered a noxious weed at the present time.
This post is part of the Floral Friday Fotos meme.