Symphyotrichum novae-angliae, commonly called New England aster, is a native perennial which is most often found in moist prairies in the eastern half of the US.  It is hardy to zone 4 and heat tolerant to zone 8, and although it is large and needs some space it is not invasive and does fine in the garden.  It grows to 3 to 6 feet and spreads to 2 to 4 feet.  Plant more than one for a real show.  The size depends on the moisture provided and the strain that you have.  Pinching back in July will keep it shorter and delay flowering.  Daisy type flowers with purple rays and yellow centers that are about an inch wide, appear in in abundance in late August and September.  The plant likes full sun and is loved by bees and butterflies. Cut back to the ground in fall to avoid seedlings. The genus name comes from the Greek symph, meaning coming together, and trich, meaning hair; in possible reference to the flower anthers.