The plants exhibit a color ranging from vivid to deep green. They are made up of slender, hair-like, single-rowed, non-branching filaments. Typically, these filaments have firm, layered walls and form loosely tangled masses. There is no specific attachment structure. The filaments are somewhat rigid and may have a slight curl, with cells that are either cylindrical or slightly swollen and roughly 1-2 times longer than they are wide. The chloroplasts within these cells have a moderately to densely reticulated and lobed appearance and contain numerous pyrenoids.