bladderwracks

Noun

bladderwrack (usually uncountable, plural bladderwracks)

1. (usually) Fucus vesiculosus, a seaweed in which iodine was first discovered.
   • Someone stood on a string of bladderwrack and made it pop, and some distance away the tide was turning.2016, Sarah Perry, The Essex Serpent, Serpentʼs Tail (2017), page 87

   Synonyms:

   black tang, rockweed, bladder fucus, sea oak, black tany, cut weed, dyers fucus, red fucus, rock wrack