Typically these unusual perennials are twiners or scramblers through other plants, or make short bushy plants. They can be trained up fences, pergolas etc. Mainly grown for their pendent bell-shaped flowers, in a range of colours and often intricately marked. Related to Campanula.
Codonopsis in the wild are pollinated primarily by bees, often solitary species. Presumably the same is true in cultivation, though the evidence is not clear.