Eichhornia crassipes
Heterostyly has evolved independently in over 25 different plant families, including the Oxalidaceae, Primulaceae, Pontederiaceae, and the Boraginaceae. These families do not exhibit heterostyly across all species, and some families can exhibit both mating systems, such as among species in the genus "Eichhornia" (Pontederiaceae). For example, "Eichhornia azurea" exhibits distyly, whereas another species in the same genus, "Eichhornia crassipes," is tristylous.