Purple top vervain, also named tall verbena, is a member of the verbena family cultivated as a flowering annual or herbaceous perennial plant. It is native to tropical South America where it grows throughout most of the warm regions.
The tall, slender-stemmed plant rises from a cluster of leaves at the base, which becomes woody over time. The stems are square in cross-section and hairy. The purple top vervain has lavender to rose-purple flowers held in tight clusters on long, almost leafless stems up to 1 m high.