Trimonoecy, also called polygamomonoecy, is when male, female, and hermaphrodite flowers are on the same plant.
[2] It is a monomorphic sexual system along with monoecy, gynomonoecy, and andromonoecy.
It is hypothesized that trimonoecy originated from gynomonoecy.
[3] Trimonoecy occurs in plant families like Anacardiaceae, Apiaceae, Araliaceae, Chenopodiaceae, Fabaceae, Orchidaceae, Palmae, and more.
[5]: 309 Trimonoecious species include: