noun
- the small, flat, heart-shaped structure that develops from a fern spore and bears the reproductive organs
Usage: botany
Examples
- The prothallus is the sexual phase in the fern life cycle.
- Students examined the tiny prothallus under a microscope in botany class.
- The prothallus produces both male and female reproductive structures.
- After fertilization occurs on the prothallus, a new fern plant begins to grow.
- The green, leafy prothallus is much smaller than the mature fern.
- Moisture is essential for the prothallus to complete reproduction.