Scouleria aquatica is very similar and occurs in the same habitat, but has unistratose to occasionally bistratose areas in the margins, and peristome teeth. Partially bistratose specimens of S. aquatica have often been misidentified as S. marginata. The leaves of S. aquatica may be more contorted than S. marginata when dry. Scouleria marginata is usually indistinguishable from S. aquatica in the field, requiring a voucher specimen or field microscope to confirm identity, but on younger, non-eroded leaves the distinctly thickened and rounded leaf borders of S. marginata may be readily evident with a 20X hand lens. The leaves of S. marginata may also be blacker and narrower than those of S. aquatica. Scouleria marginata also exhibits a tendency to develop yellowish or golden hues not seen in S. aquatica (COSEWIC 2002x; Lea et al 2006).
Source: British Columbia Conservation Data Centre