Laminaria digitata (Hudson) J.V. Lamouroux (Ar/A)

This kelp is characterized by deep divisions of the blade (Image A), which can be weak or absent in southern and deep-water collections (Image B), with solid stipes of varying length and thickness. The non-digitate morphs take on the appearance of squat Saccharina latissima (Linnaeus) C.E.Lane, Mayes, Druehl & G.W.Saunders , but can be distinguished by the presence of mucilage ducts (Image C) in the blade of L. digitata. Individuals, especially in more northerly waters, are easily confused with Hedophyllum nigripes (Rosenvinge) Starko, S.C.Lindstrom & Martone, the latter distinct by the presence of mucilage ducts in the stipe (Longtin & Saunders 2015). Molecular identification is best if absolute certainty is required.

A kelp of semi-exposed to exposed habitats, typically from the low intertidal to shallow subtidal fringe, but with genetically verified collections to 30 m in northerly waters. We have genetically verified collections ranging from northern NL (Island) (with records from Churchill, MB; Saunders & McDevit 2013) to CN (McDevit & Saunders 2010, Longtin & Saunders 2015).

GWS005900

Image A. Strongly digitate specimen from an exposed site at Beaver Harbour, NB (GWS005900).

GWS007230.JPGImage B. Non-digitate specimen from depth (20 m) at a sheltered site in Bonne Bay, NL (GWS007230).

GWS032368.jpgImage C. Mucilage duct (arrow) in the blade (Lepreau, NB; GWS032368).