List three strategies that a bisexual chasmogamous flower can evolve to present self pollination.

Three strategies are: 1) Dichogamy 2) Herkogamy 3) Heterostyly
1) Dichogamy : Maturation of male and female sex organs at different times. These are two types.
a) Protandry : Male sex organs mature earlier than female sex organs. Eg : Sunflower
b) Protogyny : Female sex organs mature earlier than male sex organs. Eg : Solanum
2) Herkogamy : Anthers and stigmas are arranged at different heights Eg : Hibiscus, and in different directions. Eg : Gloriosa.
3) Heterostyly : Presence of styles of different lengths in the flowers of same species.
Eg : Primula-diheterostyly.