Grammitids

Grammitids are a family of leptosporangiate ferns, formerly classified in the family Polypodiaceae. They are a diverse group, with over 700 species described. These ferns are typically epiphytic, growing on trees and other plants, but some are terrestrial. They are found in tropical and subtropical regions worldwide, with a particular concentration in the Neotropics and Southeast Asia.

The fronds of grammitids are usually small and simple, often entire or deeply lobed. Many species have a creeping rhizome, from which the fronds emerge. Their sori, clusters of sporangia, are often round and arranged in rows on the underside of the fronds. The spores are typically trilete.

Recent phylogenetic studies have indicated that the traditional circumscription of Grammitidaceae may be polyphyletic, and some genera previously included in this family are now placed in other fern families. Research continues to refine the understanding of their evolutionary relationships and taxonomic placement. Despite taxonomic changes, grammitids remain a significant component of many tropical and subtropical forest ecosystems, contributing to biodiversity and ecological processes. Their small size and epiphytic habit make them an interesting subject for ecological and evolutionary research.