Why is the fern frond so firm?

The firmness of a fern frond is primarily due to its structural composition, particularly the presence of lignin and specialized cells that provide rigidity. Additionally, the arrangement of cells in the frond, including thickened cell walls and vascular bundles, contributes to its strength and resilience. This firmness helps the frond support itself while effectively capturing sunlight for photosynthesis. Overall, these adaptations enable ferns to thrive in various environments.