Stamens 5, free, the filaments long, straight; anthers dithecal, located at the throat, lacking appendages.
Stamens 5, epipetalous, or sometimes free and then filaments flat, strongly flexuose; anthers dithecal or monothecal, lacking appendages.
Anthers tetrasporangiate, dithecal; leaves pinnate to palmately veined; stamens usually twice the number of corolla lobes, occasionally reduced and equaling the corolla lobes 13 13.
Androecium: stamens 4-5(-12), isomerous, alternipetalous, sometimes strongly zygomorphic and adnate to corolla tube or mouth, rarely some staminodal or even obsolete (Hoppea): anthers tetrasporangiate, usually introrse (extrorse in Gentiana) and dithecal; dehiscing via a longitudinal slit or rarely by terminal pores (Exacum); occasionally connate (Voyria); occasionally connective with one to two apical glands (Sebaea); rarely with long thread-like projections (Urogentias).
Androecium: stamens isomerous, alternipetalous and adnate to corolla-tube; anthers tetrasporangiate and dithecal, dehiscing via longitudinal slits; connective forming a small apical point.
Androecium: stamens [1 (Usteria)-]4-5(-16), isomerous, alternipetalous, adnate to corolla: anthers bisporangiate or tetrasporangiate, dithecal and introrse; dehiscing via longitudinal slits; usually isostylous, occasionally heterostylous (Gelsemieae); usually free, rarely connivent (Gardneria).