Parmeliaceae
Cetraria islandica
Iceland moss · Fjallagrös
- Kingdom
- Fungi — not a plant
- Part used
- whole
- Native range
- Arctic and alpine heath across the northern hemisphere
- Morphology
- A lichen, not a moss — an upright branching thallus to about ten centimetres, olive-brown above and paler beneath, with fringed margins. A symbiosis of a fungus and an alga, not a single organism.
What is in it
Evidence
Modest evidence as a demulcent for dry cough and throat irritation; the EMA lists it as a traditional-use registration. The mechanism is mucilage coating irritated tissue.
Safety
Well tolerated. High mucilage content slows absorption of other drugs. Lichens accumulate heavy metals and radionuclides from the atmosphere, which matters for material collected near industry — Scandinavian reindeer lichen was significantly contaminated after Chernobyl.
Interactions: Slows absorption of drugs taken concurrently
Regulatory: EMA traditional-use registration. Permitted as a food and as a listed ingredient.
Historical use
A famine food and medicine across Iceland and Scandinavia, boiled to remove the bitterness and mixed into bread and porridge. Used across northern Europe for cough, sore throat and digestive complaints.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Iceland moss is not a moss, and — more interestingly — it is not one organism. A lichen is a partnership between a fungus and an alga or cyanobacterium, so intimately combined that it was mistaken for a single species for the whole of the period this collection covers. Some are now understood to involve a third partner, a yeast, discovered as recently as 2016.
That is worth pausing on: a "plant" that European medicine used for centuries turned out to be a composite of two or three kingdoms of life.
Lichens also have no roots and take everything from the air, which makes them excellent pollution monitors and poor things to gather near a road. It is also why Scandinavian lichen — and the reindeer that eat it, and the people who eat the reindeer — carried measurable caesium for years after Chernobyl.
Nomenclature verified against GBIF backbone taxonomy.