Cells robust, linear to lanceolate with rounded to capitate ends
Striae parallel
Apical porefield present at each pole
Rimoportula present near each apex
Frustules are robust and typically needle-like. Cells typically form radiate colonies with cells attached by mucilage pads.
Synedra ulna was recently separated, with many other freshwater taxa, and is now considered to reside in the genus Ulnaria