Ganoderma sessile
Ganoderma curtisii, and Ganoderma tsugae

Ganoderma applanatum Ganoderma curtisii
Ganoderma sessile Ganoderma tsugae

Common name: Reishi, lingzhi, varnish shelf, artists conk.

Description: All Ganoderma species are polypores with a bright white pore surface that bruises brown when touched or scratched. They all produce brown spores, but unlike most gilled mushrooms, it can be difficult to obtain a spore print from Ganoderma mushrooms. The spore deposits are usually found coating the tops of the caps at full maturity.

Spore prints can be sometimes be obtained in the wild by leaving the mushroom attached to its’ substrate and pinning a piece of foil or paper to the underside of the fruitbody. Leave the foil or paper in place until a visible spore deposit is observed.

Ganodermas have a bright, white, outer growth margin while growing. As growth continues, the margin maybegin to change color and develop a tough skin that has a shiny lacquered appearance in many species.

Ganoderma applanatum is a perennial, hard, woody, sessile conk. When young, it is grayish-white in color, with a dull non shiny texture. It later turns brown after becoming covered in spores. The cap ranges from approximately 2-30 inches across, and the pore surface contains 4-6 pores per mm. The tubes are approximately 4-12 mm long. Spores 8-12 x 6.5-8 microns, more or less elliptical, with a truncated end.

Ganoderma sessile is an annual, red, laccate (lacquered-appearing), sessile conk, approximately 3-16 inches in diameter. It is found on tree trunks or in a rosette growing closer to the ground from tree roots. It is occasionally stipitate when growing in an area that allows for the collection of excess carbon dioxide, but not necessarily.

The flesh is soft, rubbery and bendable, and the outer growth margin, when cut or damaged, will produce a resinous liquid that resembles tree sap when dried. The internal flesh varies in color from cream white when young to a deep chestnut brown at maturity (often much darker than the context of G. curtisii). Shape is highly variable depending on the growing environment. The pores are often variable in shape and size, 2-4 per mm. Tube length is approx. 8-20 mm. Spores ellipsoid-ovate and truncate at one end, 9–11 x 5–7 microns.

Ganoderma curtisii is an annual, red, laccate, stipitate conk, approximately 3-6 inches across, with the stem ranging from 2-5 inches in length. The white growth margin ages to a bright yellow before finally turning a deep red with purple hues at full maturity. The internal flesh of the cap is much lighter at maturity than G. sessile, and contains streaks of a dark shiny melanoid substance.

The lacquered skin is less shiny than that of G. tsugae and G. sessile, having a more of an eggshell or matte-like finish. Often mistaken for G. lucidum, which is a European species more closely related to G. tsugae, G. curtisii is most closely related to the Chinese species G. lingzhiG. curtisii is an extremely rare find in Michigan. 4-6 pores per mm, tube length up to 10 mm. Spores ellipsoid-ovate and truncate at one end, 9–11 x 5–7 microns.

Ganoderma tsugae is an annual, glossy conk ranging from 2-12 inches in diameter with a laterally attached stipe (though sometimes the stipe is absent). The lacquer of G. tsugae is much shinier than any of the other Ganoderma species in Michigan. The internal flesh is bright white all the way into maturity, maintaining a very spongy/soft texture. Approx. 4-6 pores per mm, tubes up to 20 mm long. Spores 13-15 x 7.5-8.5 microns, more or less elliptical, sometimes with a truncated end.

Ecology/associated hosts: Ganoderma mushrooms are saprotrophic, white rot, wood-decaying fungi found on dead or dying hardwoods and occasionally conifers.

G. applanatum is an extreme opportunist found on a wide range of hardwood and conifer species.

G. sessile and G. curtisii are found predominantly on Oak and Maple, occasionally occurring on other trees such as Locust, Apple, Elm, Spruce, Fir, and Pine.

G. tsugae is found predominantly on Eastern Hemlock (Tsuga canadensis), but also occasionally found on Birch and Maple in areas with Eastern Hemlock growing nearby.

Poisonous/harmful look-alikes: There are no poisonous lookalikes, but it is important that all Ganoderma mushrooms be carefully inspected for mold, as many specimens that are past their prime can harbor molds that can be harmful. 

Harvest: The pore surface should be bright white at harvest; specimens with a darkened or moldy pore surface should be avoided. Softer varieties such as G. tsugae and G. sessile can be cut with a knife where they attach their tree host, or just above the ground. G. sessile often grows very close to the ground in lawns and contains a lot of debris like leaf litter grass and dirt, so one should be careful that none of the inclusions are harmful plants (they can sometimes be observed with poison ivy growing right through them). Ganoderma mushrooms can also be pulled off of their substrate and trimmed with a sharp pair of scissors. G. applanatum is nearly impossible to cut, so it is most often broken off of its host tree and the remaining bits of tree bark/wood at the base are scraped off with a tool.

Possible allergic reactions: People taking medications should consult their physician before consuming Ganodermas such as reishi as there have been reports of elevated liver enzymes when reishi is combined with certain medications. Some people may have a reaction that causes a skin rash, but this disappears when use is discontinued. Stomach upset is another possible side effect.

Storage: Reishi will keep fresh for at least 3-5 days under refrigeration. These mushrooms stored in a paper bag rather than plastic bags. The most common method of storage is drying. The mushrooms will dry much quicker if sliced into strips, but harder varieties, such as G. applanatum, may require a saw for slicing. Slicing also provides an opportunity to inspect the mushrooms for bugs that have burrowed inside. Drying should be performed at low temperatures with lots of airflow; higher temperatures will cause the internal flesh to ferment and produce a fishy odor. Once dried they should be sealed in glass jars, vacuum sealed, or stored in ziplock bags.


Ganoderma applanatum Ganoderma curtisii
Ganoderma sessile Ganoderma tsugae


Murrill, W.A. 1902. The Polyporaceae of North America: I. The genus Ganoderma.

Murrill, W.A. 1908. Polyporaceae, Part 2. North American Flora. 9(2):73-131

Ganoderma Diseases of Perennial Crops

Report of the Michigan Academy of Science, Volume 7