Lycopodiopsida is a class of vascular plants commonly known as clubmosses. These plants are characterized by their small, scale-like leaves and reproduce using spores rather than seeds. They are among the oldest living lineages of vascular plants, with a history dating back over 400 million years. Clubmosses typically grow in moist, shaded environments and can be found in various habitats, including forests and grasslands. They play a role in their ecosystems by providing ground cover and contributing to soil stability. Some species are also used in traditional medicine and as ornamental plants.