The peculiar combination of hydrophytic and xerophytic characteristics in the stem anatomy of Equisetum, such as the presence of a hollow stem with a silica-rich epidermis and air canals, is an adaptation to its wetland habitat. The hollow stem aids in buoyancy while the silica-rich epidermis provides mechanical support and protection against herbivory. The air canals facilitate gas exchange in waterlogged conditions, allowing Equisetum to thrive in both wet and dry environments.