1. Calyx campanulate; lobes 5, subequal , as long as tube.

2. Flowers nodding , campanulate or spreading , 3-8cm across .

3. Calyx tubular, campanulate, or cup-shaped, apex truncate to deeply lobed, sometimeswithabaxial glands, leathery, falling with petals and stamens.

4. Calyx campanulate, tubular, or funnelform, sometimes 2-lipped, usually truncate or shortly 5-dentate .

5. Calyx campanulate or cup-shaped, 5-lobed, often 10-ribbed basally and plicate in bud.

6. Under the condition of applying scale test of UNITANK process, rubber film aerator and campanulate corundum aerator have been investigated.