This kelp species is characterized by regular to irregular, shallow to deep divisions of the blade (Image A), although in BC (not as common in the Arctic and NW Atlantic) specimens commonly display entire blades (Image B). It is best distinguished from Laminaria digitata (Hudson) J.V.Lamouroux and Saccharina latissima (Linnaeus) C.E.Lane, Mayes, Druehl & G.W.Saunders by the presence of mucilage ducts in the stipe (Image C) (Longtin & Saunders 2015). Molecular identification is best if absolute certainty is required.
Although widely distributed in BC, this is a more northerly species in the NW Atlantic, found at semi-exposed to exposed habitats, typically from the low intertidal to the shallow subtidal fringe, but with genetically verified collections to 13 m in more northerly waters. We have genetically verified collections ranging from northern ME to the Bay of Fundy, NB, but these populations appear to be unstable outliers (Longtin & Saunders 2016). Excepting the previous, this species has genetically verified records from BC (McDevit & Saunders 2010), south Baffin Island, NU, to southern NL, and Churchill, MB (Saunders & McDevit 2013).
Image A. Specimen with a divided blade from Haida Gwaii, BC (GWS021105).
Image B. Specimen with an entire (albeit tattered) blade from Prince Rupert, BC (GWS005108).
Image C. Mucilage ducts (MD) in stipe of specimen from Grand Manan, NB (GWS003773).