QuestionsHow to growFlowersBorder Perennial Flowerswhat is this plant? 0 Vote Up Vote Down Jacinta Byrne asked 13 years ago this plant suddenly appeared; I think it may have hitch-hiked in on the Stipa it’s right beside. It’s about 3-4 ft tall, with sparse, lance-like leaves. Thank you! 1 Answers 0 Vote Up Vote Down Gerry Daly Staff answered 6 years ago This is Verbena bonariensis, or Buenos Aires verbena, or purple top. It sheds lots of seeds and self-sows freely.