Inedible
Tinder Conk
Fomes fomentarius
A gray, hoof-shaped bracket with a pore surface underneath. Chaga has no pores on its black mass and no bracket shape.
Chaga
Inonotus obliquus
Inedible, used in teas
Also called clinker polypore, cinder conk, birch canker.
Chaga is a black, cracked growth on living birch trees that looks like burnt charcoal. It is a sterile mass of fungal tissue and wood, rusty orange inside, not a cap. It is too hard to eat and is ground and steeped as a tea.
The tell
A black, deeply cracked, charcoal-like lump on a living birch, rusty orange-brown inside.
Field marks
What to look at
Cap, underside and stem show in a photo. The spore print does not, and it is often the deciding check.
- Cap
- No cap. The visible part is an irregular, sterile mass bursting from the trunk, black and deeply cracked like burnt charcoal on the outside.
- Underside
- None on the black mass. The spore-producing stage is a thin brown pore crust that forms under the bark after the tree dies and is rarely seen.
- Stem
- None. The mass grows directly from the trunk.
- Flesh
- Hard and corky, rusty yellow-brown to orange-brown, often with paler streaks near the wood.
- Spore print
- Not produced by the black mass.
- Size
- Usually 4 to 16 inches (10 to 40 cm) across.
Where and when
Where and when it grows
- Habitat
- Northern hardwood and mixed forests, on the trunks of living birch, often at an old wound or broken branch.
- Grows on
- Living birch; rarely other hardwoods such as alder.
- Season
- Year-round. The mass grows slowly over many years.
- Range
- Northern North America wherever birches grow, from Alaska and Canada through the northern states and south along the Appalachians.
Lookalikes
What the chaga gets confused with
Each card says how to tell the two apart.
Birch burl
A rounded swelling of the tree's own wood, covered in bark, and woody tan inside rather than black and crumbly outside with orange-brown flesh.
Black knot (Apiosporina morbosa)
Smaller black, lumpy swellings on the twigs and branches of cherry and plum, not on birch trunks.
More side-by-side comparisons
Edibility
What the field guides say
Inedible, used in teas
Field guides list chaga as inedible because it is hard and corky. It is broken into chunks or ground and steeped in hot water as a tea, a use recorded for centuries in Russia and northern Europe. Chaga contains high levels of oxalate, and a published case report links kidney damage to heavy, long-term chaga powder use.
This page states what field guides record. It is not advice to eat, taste or handle anything, and a photo cannot settle edibility. If someone has eaten a wild mushroom that may be toxic, call poison control (1-800-222-1222 in the US) right away, before symptoms start: the deadliest species act hours later.
FAQ
Questions about the chaga
What is chaga used for?
It is ground or broken into chunks and steeped in hot water as a tea, and it is sold as powders and extracts. The tea tradition goes back centuries in Russia and northern Europe.
What does chaga look like?
A black, deeply cracked lump bulging from the trunk of a living birch, looking like burnt charcoal. Broken open, it is rusty orange-brown and corky inside.
Does chaga grow on trees other than birch?
Almost all chaga grows on birch. It is occasionally reported on other hardwoods such as alder, but birch is the host field guides describe.
Sources
Where these facts come from
- Inonotus obliquus
MushroomExpert.com
- Inonotus obliquus
Fungi Growing on Wood, Gary Emberger (MushroomExpert.com)
- Inonotus obliquus
Index Fungorum
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