Sexual system
A sexual system is a pattern of sex allocation or a distribution of male and female function across organisms in a species. Terms like reproductive system and mating system have also been used as synonyms. The distinction between sexual systems is not always clear due to phenotypic plasticity. Sexual systems are viewed as a key factor for genetic variation and reproductive success, and may have also led to the origin or extinction of certain species. Interests in sexual systems go back to Darwin, who found that barnacles contain species that are androdioecious and some that are dioecious. Types of sexual systems 
In angiosperms there are monomorphic sexual systems where a species has combination of hermaphrodite, male, and/or female flowers on the same plant. Monomorphic sexual systems include monoecy, gynomonoecy, andromonoecy, and trimonoecy. There are also dimorphic sexual systems where individual plants within a species only produce one sort of flower — hermaphrodite, male, or female. Dimorphic sexual systems include dioecy, gynodioecy, androdioecy, and trioecy. Mixed sexual systems are where hermaphrodites coexist with single sexed individuals. This includes androdioecy, gynodioecy, and trioecy. What determines whether a flower is male, female, or hermaphroditic is the presence of a stamen — which contains male gametes — and/or pistil — which contains female gametes. Male ( staminate) flowers only have a stamen. Female (a.k.a. pistillate) flowers only have a pistil. Hermaphrodite (a.k.a. perfect, or bisexual) flowers have both a stamen and pistil. The sex of a single flower may differ from the sex of the whole organism: for example, a plant may have both staminate and pistillate flowers, making the plant as a whole a hermaphrodite. Hence although all monomorphic plants are hermaphrodites, different combinations of flower types (staminate, pistillate, or perfect) produces distinct monomorphic sexual systems. (See Plant reproductive morphology for further details on plant sexual systems.) List of sexual systems

References 

 
Developmental biology
Evolutionary biology
Taxonomy (biology)