This species can have small to large (>1 m) yellowish to dark brown blades characterized by a weak to moderate midrib and typically fimbriae along the margins of the stipe (Image A). It can be confused with Agarum clathratum Dumontier, especially when the blade develops holes (Image B), but that species has a narrower, albeit more prominent, midrib, is typically darker in colour, and never has fimbriate margins.
We have genetically verified records from throughout BC for this relatively common subtidal (23 m, most certainly it grows deeper) to low intertidal species. It tends to avoid wave exposure and extend shallower (into the intertidal) at sheltered sites.
Image A. Specimen from Saxe Pt., Victoria, BC (GWS004270) displaying a moderate, albeit broad, midrib, and fimbriae along the stipe margins.
Image B. A drift specimen from Haida Gwaii, BC (GWS044780), which has numerous holes in the blade similar to Agarum clathratum Dumontier.
Seaweed of Canada 