Sphenophyta

Sphenophyta is a division of vascular plants that are commonly known as horsetails. This group of plants is characterized by jointed stems, often with a hollow central pith, and whorls of leaves and sporangiophores at the nodes. These leaves are typically small and scale-like, lacking the photosynthetic function of broader leaves. Reproduction in Sphenophyta occurs through spores produced in cone-like structures called strobili, which are often located at the apex of fertile stems. The life cycle involves an alternation of generations, with a dominant sporophyte generation and a free-living gametophyte generation. Extant horsetails belong to the single class Equisetopsida, and the order Equisetales. Fossil evidence indicates that Sphenophyta was a much more diverse and widespread group during the Carboniferous period, with some ancient forms reaching tree-like proportions. Today, horsetails are found in a variety of habitats, often in moist or damp environments. They are perennial plants, typically growing from underground rhizomes. While some species are herbaceous and die back in winter, others can persist with evergreen foliage. The primitive vascular structure and unique morphology of Sphenophyta make them of significant interest in the study of plant evolution.