Reishi mushrooms are one of the easiest mushrooms to identify, and a great place to start for beginning mushroom foragers. They have no poisonous look-alikes, so they’re relatively safe as well. Though reishi are generally too tough to eat, their medicinal properties have been well documented.
There are a number of different reishi species, and each grows in a different region around the world. For the most part, their medicinal properties are the same and there is some argument that they’re actually the same species occupying different habitat niches.
All species grow on dead and dying trees and produce annually. Once you find reishi on a particular log or stump, they will continue to produce there every year until they’ve consumed all the wood substrate.
Reishi mushrooms are also known by the names lingzhi, mushroom of immortality, ten-thousand-year mushroom, herb of spiritual potency, varnish shelf and artists conk.
REISHI MUSHROOM IDENTIFICATION
The mushroom itself is kidney or fan-shaped and has a distinctive red to orange color, and a shiny lacquered finish on the top. It’s a polyspore, so it lacks gills, but the underside is white (or tan or grey in older specimens) and has pinprick like dots. The flesh on the underside develops a brown/tan bruise when pressed.
Only harvest fresh mushrooms with white undersides as they can potentially harbor dangerous molds when the mushrooms are past their prime or bruised and damaged. Since they’re easily bruised and damaged during harvest, reishi should be preserved quickly after harvest.
They vary in size from an inch wide to a foot wide and can be as much as 2 inches thick. More commonly, they’ll be 4 to 6 inches wide and 1/2 inch to 1 inch thick.
New growth on the leading edge comes in as white and gradually changes to red-orange. Young mushrooms that are rapidly growing may be mostly white as they emerge from the wood. The bright red-orange cap that is characteristic of hemlock reishi will come as they mature.
As reishi get older, their flesh becomes tougher and the bright cap begins to dull. On my land, reishi rarely make it more than a few days before the slugs begin to devour them. The harvest season in central Vermont is right around the summer solstice, and I go out daily to make sure I catch the mushrooms before they’re slug eaten.
Reishi grows horizontally out of their host log, often with a very short or non-existent stem. They have a strong but pleasant woodsy scent, a bit like decomposing leaf mulch.
Spores emerge from the bottom side of the mushroom, and on logs where they’re growing one above the other, you’ll see spores released by the upper mushrooms dulling the caps of the mushrooms below. The spore print in all species is brown.
REISHI MUSHROOM SPECIES
Identifying reishi mushrooms varys a bit from region to region as different species have evolved based on location.
- Ganoderma lucidum – Is the species used in traditional Chinese medicine. It grows on hardwood (especially oaks) in warmer regions, such as Asia, the south Pacific, southern Europe and the Southeastern United States.
- Ganoderma tsugae – Found in the Northeastern United States, the species name “tsugae” means “hemlock tree” which tells you where you should begin looking for this species. Though it’s almost always found on hemlock, it can occasionally be found on birch or maple if they were growing close to hemlock. They can be found freshest between May and July. This species is also known as hemlock varnish shelf.
- Ganoderma applanatum – A particularly hard and woody reishi species, varying in size from 2 to 30 inches wide. Color is duller than others and lacks a lustrous shine. Very difficult to cut, and often must be cut with a saw into strips for drying. This species is an opportunist and can be found on many different tree species, both hard and soft wood.
- Ganoderma curtisii – Distributed from Massachusetts to Nebraska, this species has an especially dramatic ochre colored cap, that dulls as the mushroom ages. It has a matte rather than lacquered finish on its cap. Found on hardwood logs, usually oak or maple, but occasionally other hardwoods as well.
- Ganoderma sessile – A red shiny species that grows 3 to 16 inches across. The flesh is very soft and bendable, and unlike other species, if damaged the outer growth margin will produce a sap like resin. Found on hardwood, usually oak or maple, but occasionally other hardwoods as well.
- Ganoderma oregonense – As its name suggests, this species is native to the pacific northwest where it grows on conifers. The fruiting body is very large and can be up to a meter across.
Other species include: Ganoderma lingzhi, Ganoderma capense, Ganoderma carnosum and Ganoderma resinaceum.