Sep 5; cor tubular, soon becoming deeply cleft; anthers united at base into a ring around the style; ovary 2-locular; style clavate, undivided; fr obovoid, opening by terminal valves; fls in dense head-like umbels subtended by a leafy involucre. 20, Europe and Medit. reg.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.