Fls 4-merous; cal deeply cleft into narrow segments; cor rotate, the tube short, the lobes with 1 or 2 large glands below the middle, the gland ±completely surrounded by a usually fimbriate membrane; stamens on the cor-tube, the filaments dilated below and often connate at base; some fimbriate scales often present just internal to the stamens or between them; ovary with a ±elongate style and capitate stigma; perennial herbs with opposite or whorled lvs and fairly large fls in large terminal paniculiform cymes. 12, mostly w. U.S. (Often included in Swertia)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.