Petalostemon purpurea syn Dalea purpurea 'Stephanie'

Purple prairie-clover is a popular prairie perennial with delicate, foliage and showy purple flowers in summer. Numerous slender stems rise 30-60cm. A drought tolerant species. Beautiful foliage even when not in flower. The flowers are like purple/pink bumle bees similar to those of Sanguisorba but nicer. Collect seed and it will grow on bare soil and being a legume it will improve it too. Excellent for meadow looks and the border or gravel and sand gardens.  Not my own image, I must wait for these to flower next summer.