Incompatibility of Meristematic and Filamentous Growth in the Fern Gametophyte

Gametophytes of Pteridium aquilinum can be maintained in red light as either 1‐ or 2‐dimensional structures. The mode of growth realized in red light is dependent upon the activity of the meristem. An active meristem in a 2‐dimensional structure will permit a continued development of that structure. A breakdown in meristematic activity results in filament formation. It is suggested that a group of actively dividing cells in some manner inhibits cell elongation and thus prevents filament formation in red light.