What is "fucus vesiculosus"

Bladder \Blad"der\ (bl[a^]d"d[~e]r), n. [OE. bladder, bleddre, AS. bl[=ae]dre, bl[=ae]ddre; akin to Icel. bla[eth]ra, SW. bl["a]ddra, Dan. bl[ae]re, D. blaar, OHG. bl[=a]tara the bladder in the body of animals, G. blatter blister, bustule; all fr. the same root as AS. bl[=a]wan, E. blow, to puff. See Blow to puff.]

1. (Anat.) A bag or sac in animals, which serves as the receptacle of some fluid; as, the urinary bladder; the gall bladder; -- applied especially to the urinary bladder, either within the animal, or when taken out and inflated with air.

2. Any vesicle or blister, especially if filled with air, or a thin, watery fluid.

3. (Bot.) A distended, membranaceous pericarp.

4. Anything inflated, empty, or unsound. ``To swim with bladders of philosophy.''
   --Rochester.

   Bladder nut, or Bladder tree (Bot.), a genus of plants ( Staphylea) with bladderlike seed pods.

   Bladder pod (Bot.), a genus of low herbs ( Vesicaria) with inflated seed pods.

   Bladdor senna (Bot.), a genus of shrubs ( Colutea), with membranaceous, inflated pods.

   Bladder worm (Zo["o]l.), the larva of any species of tapeworm ( T[ae]nia), found in the flesh or other parts of animals. See Measle, Cysticercus.

   Bladder wrack (Bot.), the common black rock weed of the seacoast ( Fucus nodosus and Fucus vesiculosus) -- called also bladder tangle. See Wrack.

Fucus vesiculosus, known by the common name bladder wrack or bladderwrack, is a seaweed found on the coasts of the North Sea, the western Baltic Sea, and the Atlantic and Pacific Oceans, also known by the common names black tang, rockweed, bladder fucus, sea oak, black tany, cut weed, dyers fucus, red fucus, and rock wrack. It was the original source of iodine, discovered in 1811, and was used extensively to treat goitre, a swelling of the thyroid gland related to iodine deficiency.