3–5, or 6–10; 1 whorled, or 2 whorled; isomerous. Calyx 3–5; 1 whorled; basally gamosepalous. Calyx lobes markedly shorter than the tube to markedly longer than the tube. Calyx regular; imbricate. Corolla when present, 3–5; 1 whorled; polypetalous, or gamopetalous (rarely, basally). Corolla lobes markedly longer than the tube. Corolla imbricate.