A lovely, under-utilized flower for midsummer through fall is purpletop vervain, or verbena bonariensis, often called simply verbena. This tender perennial is native to South America, sometimes erroneously called Brazilian vervain (a different plant entirely). ‘Bonariensis’ derives from Buenos Aires, but this plant is native to all warm areas of the southern continent from Columbia to Chile, Brazil, and Argentina.
Similar species
When we hear the word verbena, what comes to mind first are the bright annual or trailing verbenas (Glandula x hybrida) used extensively in hanging baskets and pots. There are also low-growing moss verbenas. Hoary or blue vervain (Verbena hastata) is a wildflower native to the central US, a nice choice for native meadows.