Thelophyta is a term that refers to a group of simple, non-vascular plants, primarily encompassing certain types of green algae. These organisms are primarily aquatic and can be found in various freshwater and marine environments. Thelophyta are characterized by their simple structures and lack of complex tissues, distinguishing them from higher plant groups. They play a crucial role in aquatic ecosystems, contributing to oxygen production and serving as a food source for various organisms.