Cetraria islandica   Iceland Moss, Iceland Lichen  Family: Parmeliceae     
PART USED: Entire dried plant.
FLAVOR: Bitter. ODOR: Almost none. When wet, recalls that of seaweed.
ACTIONS
1. Demulcent.[1,2]
2. Expectorant.[1,2]
3. Antiemetic.[1,2]
4. Nutritive.[2]
5. Antibiotic properties.
INDICATIONS
1. Gastritis.[1] Dyspepsia.[1] Vomiting.[1] Cachexia[1](weakness and wasting of the body due to severe chronic illness).
2. Respiratory catarrh. Bronchitis.
SPECIFIC INDICATIONS: Cachexia with vomiting.[1]
COMBINATIONS
PREPARATIONS: 3X/day
Decoction[2] of dry lichen  1-2 g in decoction.[1]
Tincture 1:5 in 40% alcohol  1-1.5 ml.[1]

ORIGIN:  Native to Northern countries.
DESCRIPTION: Thallus smooth dichotomously branching curled, greyish or greenish-brown, about 6cm long and 0.5 cm wide, curled of channelled, terminating in lobes.  The undersurface is paler with minute, depressed, white spots.
References
Constituents
Research

The properties are due mainly to the polysaccharides, however the lich acids have antibiotic properties.[1,2]
References
[1] Houven, L. et al. (1985) Acta Pharm. Fenn. 99, 94
[2] Pharmacognosy, 12th Ed. Trease, G. E. and Evans, W. C. Pub. Bailliere Tindall (1983) UK

Assessment report on Cetraria islandica (L.) Acharius s.l., thallus

Evaluation of in vitro antioxidant, antimicrobial, genotoxic and anticancer activities of lichen Cetraria islandica
Darko Grujicic, Ivana Stošic, Marijana Kosanic, Tatjana Stanojkovic, Branislav Rankovic, and Olivera Miloševic-Djordjeviccorresponding author
Abstract
In this study, the antioxidant, antimicrobial, genotoxic and anticancer activities of Cetraria islandica methanol extract were determined by using free radical and superoxide anion scavenging activity, reducing power, determination of total phenolic compounds and flavonoid contents, broth microdilution minimal inhibitory concentration against five bacterial and five fungal species, cytokinesis block micronucleus (MN) assay on peripheral blood lymphocytes (PBLs) and the microculture tetrazolium test on FemX (human melanoma) and LS174 (human colon carcinoma) cell lines. As a result of the study, we found that C. islandica methanol extract exhibited moderate free-radical-scavenging activity with IC50 values 678.38 µg/ml. Moreover, the tested extract had effective reducing power and superoxide anion radical scavenging. The minimal inhibitory concentration values against the tested microorganisms ranged from 0.312 to 5 mg/ml. The extract increased MN frequency in a dose dependent manner, but it was significant in higher tested concentrations (50, 100 and 200 µg/ml). No significant differences were observed between NDI values in all treatments and untreated PBLs. In addition, the tested extract had strong anticancer activity towards both cell lines with IC50 values of 22.68 and 33.74 µg/ml. It can be concluded that the tested extract exhibited a certain level of in vitro antioxidant, antimicrobial, genotoxic and anticancer activities.
Cytotechnology. 2014 Oct; 66(5): 803–813.
Published online 2014 Mar 4. doi: 10.1007/s10616-013-9629-4
PMCID: PMC4158017 PMID: 24590925 ncbi.nlm.nih.gov