Chaga

Where it grows

Chaga is the sterile sclerotium of Inonotus obliquus, which parasitises birch trees across the cold temperate and boreal forests of Russia, Scandinavia, Canada, and Alaska. It grows slowly over many years, eventually weakening or killing the host. The true fruitbody develops later, beneath the bark after the tree’s death, and is rarely seen.

How to recognise it

A jagged black crusty lump bulging from the trunk of a living birch. The outside is coal-black, deeply cracked, and corky — easily mistaken for charcoal. Break it open and the inside is bright rusty orange, softer and crumbly, the colour of dried apricot.

Edibility & cautions

Inedible as food but prepared as a dark bitter tea or tincture. Sustainability matters: chaga grows extremely slowly and overharvesting is depleting wild populations in eastern Europe. Chaga is high in oxalates and can interact with blood-thinning medication and worsen kidney problems; consult a doctor before regular use.

Medicinal use

Simmer broken pieces for several hours, or use a standardised dual extract. Studied for antioxidant and immunomodulatory polysaccharides; clinical evidence remains limited.