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Harmless🍽️ Edible💊 Medicinal

🟤 Bladderwrack

Fucus vesiculosus · Fucacées

🐚 Coastline🍁 North America
🧠 To remember it“Two by two, bladderwrack's bubbles do”—the paired air vesicles along the midrib are its signature, invisible on all its brown cousins without floats.
Bladderwrack — Fucus vesiculosus

🔍 Identify it without mistakes

Very common brown seaweed, immediately recognizable by its pairs of air vesicles arranged on either side of a midrib on a flat, fork-branching frond. These floats, which give it its name, form large carpets on the rocks of the mid-intertidal zone, making it arguably the most familiar seaweed of rocky beaches.

  1. flat frond branching in forks (dichotomous), olive-brown to yellow-brown
  2. pairs of round or oval air vesicles on either side of the midrib, characteristic of the species
  3. well-marked midrib along the entire length of the frond
Size30 à 90 cm
Floweringpas de floraison (algue)
Habitatrocky coasts of the North Atlantic and Baltic Sea, mid-intertidal zone, also present on the Atlantic coasts of North America

⚠️ Not to be confused with

Spiral wrack (no vesicles, high intertidal zone) and bladderwrack with single vesicles (Fucus spiralis)aucun (comestible aussi)

To tell them apart: spiral wrack grows higher up on the shore, its spirally twisted frond lacks air vesicles; bladderwrack, lower down, bears its clearly visible pairs of floats along the midrib

Knotted wrack (Ascophyllum nodosum)aucun (comestible aussi)

To tell them apart: bladderwrack bears its air vesicles in pairs on either side of a visible midrib; knotted wrack has single swellings, one by one along a strap-like frond without a distinct midrib

🍽️ Eating it

Partsfronde
Seasontoute l'année, meilleure qualité au printemps
Tastevery salty and iodized, strong, often used in small doses as a condiment rather than a vegetable

Preparation : consume in small quantities, dried and ground into powder as a salty-iodized condiment, or as an infusion; the very strong, salty iodine taste discourages eating it in large amounts, which is actually recommended given its high iodine content

💊 Healing with it

traditionally used in herbal medicine to support thyroid function (thanks to iodine) and, externally, against cellulite and for weight loss

Level of evidence : etudes-limitees pour les effets métaboliques, tradition pour le reste ; la Commission E allemande reconnaît un usage traditionnel contre l'obésité modérée — Commission E (Allemagne) — monographie Fucus vesiculosus

⚠️ avoid in case of thyroid disorders (hyper- or hypothyroidism), pregnancy, or breastfeeding without medical advice, due to its very high iodine content; possible interactions with thyroid treatments; avoid harvesting in port zones (heavy metals)

🪓 Other bushcraft uses

  • historical source of iodine and potash (soda ash) before the industrial era, burned to ash for these uses
Sources (3)

No entry replaces a certain identification in the field, or medical advice. When in doubt: don't eat it. If ingestion is suspected: poison control or 112/911.