A native of prairie, wavyleaf purple coneflower also makes a good garden flower.   This perennial grows 24- to 36-inches high and produces long drooping purple flowers around a dark central core from May through August.   Tolerant of drought heat and humidity, wavyleaf coneflower does best in full sun and medium- to dry-soil.  During the summer, it will attract butterflies. Leave the dead stems with the flowerheads attached in winter and it will attract birds.