Dark green plant with a hollow cylindrical stalk. It is usually fixed to the substrate by a small or a large expansion of the stem. The stem is simple, branched only in basal or abundantly branched from the upper third of the stem regions. The cells are irregularly arranged in a longitudinal alignment surface without polygonal or rounded view. The pemphigus stalk is fixed to the substrate by a small apresorium, consisting of two layers of cells. The cell contour is polygonal, with a parietal chromatophore with a pirenoide . Thick cuticles. Assexual reproduction through the formation of zoospores in quadriflagelados number from 4 to 8 per cell. Sexual reproduction by the formation of biflagellate anisogametas in number per cell . All stem cells are capable of forming reproductive elements, except for the attachment. The alternation of generations required  is morphologically identical.