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Plants in which proterandry or proterogyny occurs are called dichogamous.

Many hermaphrodite plants are, as first shewn by C. K. Sprengel, dichogamous; that is, their male and female organs are not ready at the same time, so that they cannot be self-fertilised.

Flowers are dichogamous when the anthers discharge their pollen either before or after the stigmas of that flower are in a condition to receive it.

Sprengel dichogamous, in which the pollen and stigma of the same flower are matured at different periods; or those called by me reciprocally dimorphic, in which the flower's own pollen is not fitted to fertilise its own stigma; or again, the many kinds in which curious mechanical contrivances exist, effectually preventing self-fertilisation.

Sprengel, C. K., on dichogamous plants, ii.