Knautia arvensis (Field scabious)
Terrific perennial similar to Scabiosa but with longer stemmed flowers offering a light airiness that is a perfect accompaniment to grasses or Euphorbia. Flowers from early spring right through to mid autumn if it gets the occasional splash of water during the heat of summer. Develops a mound of basal foliage 0.25mH x 0.30mW with flower stems reaching up to 0.5mH. Grows happily in full sun to part shade. Will gently self seed if not deadheaded but easy to remove or mulch over to control progeny.