This species has a distinctive morphology and can dominate the mid intertidal zone through parts of its range. It has an olive to greenish brown colour and typically grows attached to rock (Image A). Plants can reach a meter or more in height and the individual axes are terete to compressed and inflated locally to form buoyant vesicles (Image A). The reproductive receptacles are borne laterally along the blades and the species is dioecious with female and male receptacles being green and yellow (Image B), respectively. An unattached morph is common in salt marshes tangled among vegetation in the uppermost intertidal (Image C).
We have confirmed records from ME and throughout Atlantic Canada. A single drift specimen was collected in northern Labrador (60°14’01.9″N), NL, in September 2014 (Image D). In addition to being harvested for various uses, Ascophyllum nodosum is also notably the usual host of Vertebrata lanosa (Linnaeus) T.A.Christensen.
Image A. Image of the compressed blades with obvious inflated vesicles (mid intertidal on rock, Campobello I., NB; EGWS000020).
Image B. Male receptacles (with obvious conceptacles) borne laterally on the blade (mid intertidal on rock, Lepreau exposed biodiversity site, NB; GWS003837).
Image C. The unattached salt marsh morph tangled among the vegetation in the uppermost intertidal (‘Cottonii’ Creek, near Letete, NB; EGWS000694).
Image D. Drift male specimen collected near the Duck Islands, Torngat in northern Labrador, NL GWS039304).