Asplenium

Asplenium is a genus of ferns in the family Aspleniaceae, commonly known as spleenworts. It comprises roughly 700 species with a nearly worldwide distribution, though diversity is greatest in tropical and subtropical regions as well as temperate forests. The fronds range from small, simple blades to larger, pinnate or even tripinnate leaves. Sori are typically located on the underside of the fronds and are often linear or kidney-shaped, with indusia that can be reniform or peltate. The genus includes lithophytic, epiphytic, and terrestrial species, and many are adapted to shaded, humid environments, though some tolerate drier or exposed conditions.

Ecology and reproduction: Asplenium species reproduce by spores produced in the sori, following the fern life cycle that includes a free-living gametophyte (prothallus) stage. The broad ecological range of the genus reflects a variety of substrate preferences, from rock crevices to tree bark and forest floors.

Taxonomy and phylogeny: Asplenium is placed in the family Aspleniaceae, within the order Polypodiales. Molecular studies have helped clarify relationships within the genus, which is subdivided into several clades and subgenera, reflecting its substantial species diversity and wide ecological range.

Uses and conservation: Many Asplenium species are cultivated as ornamental ferns for shaded gardens, terrariums, and indoor displays. In the wild, they contribute to forest and rocky-habitat ecosystems, but some species are threatened by habitat loss and over-collection in certain regions.

Fossil record: The genus has a fossil record that includes pollen and leaf impressions attributed to Asplenium dating back to the Cretaceous in various regions, indicating a long evolutionary history within ferns.