Striae

Rows of areolae are arranged to form striae. Striae are usually oriented along the transapical axis. Features of the striae are important in diatom taxonomy and phylogeny, from the stria density (number of striae that occur in 10 µm), to the orientation of the striae (radiate, parallel, or convergent), to the shape of the areolae (lineolate, punctate, C-shaped) that form the striae.