Vernonia arkansana

Vernonia arkansana (also known as Arkansas ironweed and great ironweed) is a species of perennial plant from family Asteraceae found in south-central United States. The plant is 4–6 feet (1.2–1.8 m) high and 3–4 feet (0.91–1.22 m) wide. The flowers bloom from August to September and are pink-purple coloured. The cultivar 'Mammuth' is a recipient of the Royal Horticultural Society's Award of Garden Merit.