Sep petaloid, valvate in bud, commonly 4, sometimes more; pet none; staminodes present or absent; pistils numerous; fr a flattened achene, terminated by the elongate, persistent style; erect perennial herbs, or herbaceous or somewhat woody vines climbing by the prehensile lf-rachis, with opposite, simple or compound lvs and solitary or panicled, medium-sized to large fls, usually dioecious; x=8. (Atragene, Viorna) 300, cosmop. Species of the section Viorna are called Leather-flower or Curly heads.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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.JPG "(linked from Clematis columbiana)")