In botany and mycology, an organism is considered perfect if it is capable of sexual reproduction. If it isn't, it is imperfect. The term perfect has nothing to do with the quality of an organism.

The exact idea of being perfect or imperfect varies somewhat between plants and fungi.

All fungi in the division Deuteromycota cannot undergo any form of sexual reproduction.

All nonflowering seed plants are imperfect in relation some angiosperms. This is because their reproductive organs are either male or female. This does not mean one single plant would have both seed and pollen cones. So gymnosperms are either dioecious or monoecious but never both.

A flower is called perfect if it has both male and female parts. That is, it has both stamens and an ovary. If a plant has separate male and female flowers, it is dioecious. If a plant has male or female flowers on separate individuals, it is monoecious.