Euphyllophyta

Euphyllophyta is a clade of land plants within the vascular plants (tracheophytes). It comprises all plants that possess megaphylls, or true leaves with extensive branching veins, and an overtopping growth habit, in contrast to the lycophytes (Lycopodiophyta), which retain microphylls. Euphyllophyta includes two large lineages: Monilophyta, which encompasses most ferns, horsetails and whisk ferns; and Spermatophyta, the seed plants, including gymnosperms and angiosperms.

Key features include megaphyll leaves and advanced branching; in spermatophytes, seeds replace spores as the primary dispersal unit; in monilophytes, reproduction is via spores.

Fossil record: earliest euphyllophytes appear in the late Silurian to early Devonian, with Archaeopteris as an important early example showing wood and megaphylls. This lineage marks a major step in the evolution of forest-forming plants on land.

Taxonomy and relationships: Euphyllophyta is defined in modern phylogenies as a clade that is sister to Lycopodiophyta. Within Euphyllophyta, the two main lineages are Monilophyta and Spermatophyta, the latter comprising seed-bearing gymnosperms and angiosperms.

Importance: The evolution of megaphyll leaves, complex branching, and, in seed plants, seeds, contributed to the diversification of terrestrial flora and the development of forests that shaped global ecosystems from the Devonian onward.