Ganoderma tsugae
by Barbora Batokova • July 1, 2022
Ever since I learned about this mushroom's existence, I knew I had to see in person. I was mesmerized by its shiny appearance and its unique shape that evolves as the mushroom matures. Evoking the colors of the setting sun with its yellow and white margin, this red bracket fungus steals the show among the majority of polypores that sport grey, brown or whitish caps. Commonly known as the hemlock varnish shelf or the hemlock reishi, it is one of the three varnished (or laccate in Mycologese) Ganoderma species in the northeast of North America, the other two being G. sessile and G. curtisii.1 The common name has nothing to do with the poisonous herbaceous plant hemlock, but it is a reference to the eastern hemlock tree (Tsuga canadensis) it grows on, whose name is derived from a perceived similarity in the smell of its crushed foliage to the poisonous plant.
I finally found it for the first time in May 2021 during my escape trip from the city during the coronavirus pandemic to Cook Forest State Park, which is known for some of America's oldest virgin hemlock timber stands. One of the biggest factors in your ability to find a particular mushroom is being in the right place at the right time—because the hemlock reishi fruits in May and June almost exclusively on eastern hemlock trees2, I knew my chances were pretty good.
While not the true reishi (G. lucidum), the two species are closely related and resemble each other, but they have very different habitats. G. lucidum only grows in wild in China and parts of Europe on hardwoods, while G. tsugae only grows in the wild in the North American east and on eastern hemlocks. However, just like a true reishi, which has a long history of use for promoting health and longevity in China, Japan, and other Asian countries, the hemlock reishi is also believed to have medicinal properties.
- Etymology
- Taxonomic History
- Ecology
- Description
- Distribution
- Similar Species
- Edibility and Taste
- Medicinal Properties
- ID Table
Etymology
The scientific name references the appearance and habitat of the mushroom: Ganoderma is derived from the Greek ganos/γανος meaning "brightness, sheen" and derma/δερμα meaning"skin". Put the two together and you get "shiny skin." The specific epithet tsugae means hemlock (Tsuga), which is one of its most common hosts.
Taxonomic History
G. tsugae was first described by American mycologist William Alphonso Murrill in 1902 in the Bulletin of the Torrey Botanical Club, Vol. 29 based on specimens collected from decaying trunks and roots of eastern hemlock in New York, Connecticut, Massachusetts and Ohio.3 Unlike many other mushrooms, the taxonomy of this mushroom is pretty solid and hasn't changed since.
Ecology
These photos were taken in Emlenton, PA at the end of May, when the hemlock reishi begin to fruit on eastern hemlock trees.
Growing in late spring and early summer, this bracket fungus grows almost exclusively on eastern hemlock trees, although when cultivated, it grows on a wide variety of other conifers as well. It can sometimes have a second fruiting cycle in the fall, and even though it is an annual fungus, it may persist through winter. It is a white-rot saprophyte (sometimes a parasite on still living trees), degrading lignin and leaving decayed wood whitish in color and fibrous in texture.
Description
On the left, you can see a very young hemlock reishi polypore growing on a fallen eastern hemlock tree in Cook Forest State Park at the end of May. On the right is a more mature fruiting, also from Cook Forest State Park, but this time towards the end of June.
What a stunning mushroom this is! Growing solitary or sometimes in overlapping clusters on tree stumps and fallen trunks of eastern hemlocks, this polypore starts as an irregularly knobby or elongated orange structure with a plump white edge—I call this stage the marshmallow stage—before it develops into a kidney-shaped shiny red, radially furrowed bracket with a bright yellow and white margin. Eventually it becomes entirely maroon red and matte as the spores settle on top of it. The caps can range from 5-30 cm wide and between 0.5 - 3 cm thick.4
The central stem is varnished like the cap and up to 3 cm thick. It is usually around 2.5 cm long, but depending on the light conditions, it can be up to 15 cm long as the mushroom searches for preferred light conditions. In those cases, the cap is often distinctively angled away from the stem, sometimes almost at a right angle. Many people manipulate the light conditions when they cultivate this polypore to create some interesting mushroom sculptures.
The underside is whitish, becoming dingy brown in age, usually bruising brown. The tubes are 0.3 -1 cm long and the circular to angular pores are about 4-6 per mm. The white flesh is soft at first, becoming hard and corky with maturity.
A comparison of the cap and the underside of a mature hemlock reishi in Cook Forest State Park towards the end of June.
Here you can see the whitish flesh and tubes of the hemlock reishi as I split the mushroom in half. Photographed in Cook Forest State Park towards the end of June.
Distribution
On the left is a good example of the plump white edges the mushroom has when it's still growing. Photographed in Cook Forest State Park towards the end of June. On the right is an example of some of the unique shapes reishi can sometimes make :-). Photographed in Cook Forest State Park beginning of July.
Because of its distinct preference for substrate, you can only find it in northern and montane areas east of the Rocky Mountains in North America, paralleling the range of its host tree, the eastern hemlock.5
Similar Species
The three most likely lookalikes are G. sessile, G.curtisii7 and G. oregonense.8
Based on comparative genomics study with other Ganoderma species, G. tsugae diverged from their common ancestor of G. lingzhi and G. sinense about 21 million years ago.6 Now, there are about 80 described Ganoderma species, but only a few can be considered lookalikes or similar to G. tsugae.
G. sessile occurs in eastern North America, but it is associated with declining or dead hardwoods.
G. curtisii occurs in eastern North America, but it grows on deciduous trees and it is usually smaller.
G. oregonense is found in the Pacific Northwest and California on the wood of various conifers, but it is much larger, thicker, darker and duller in color and has larger spores than G. tsugae.
Edibility and Taste
Due to its tough and corky flesh, this polypore is not edible, though the fresh, soft margin can supposedly be sautéed and prepared just like the soft edges of the resinous polypore (Ischnoderma resinosum), though I haven't tried it myself.
Medicinal Properties
On the left is good example of how the stem and cap can be at a very distinct angle. Photographed in Cook Forest State Park end of June. On the right is a mature hemlock reishi. Photographed in Cook Forest State Park beginning of July.
This is a very well researched mushroom for its immunomodulatory (it can stimulate or bring down your immune system), antioxidant, anti-inflammation, anticancer, antihistamine, and lipid-lowering properties. Because it contains a large number beneficial compounds, it has become a precious cultivated species in Northeast China, where it presents an important source of pharmaceutical product.6
There are three major ways to take advantage of the medicinal properties: via a dried powder, tea, or a tincture. Making tea with hot water will allow you to extract the polysaccharides, while soaking it in alcohol or alcohol/glycerin is more effective for extracting triterpenoids.
ID Table
 |
Scientific Name
|
Ganoderma tsugae
|
 |
Common Name | Hemlock Varnish Shelf, Hemlock Reishi |
 |
Edibility | Inedible, but medicinal |
 |
Ecology
|
Saprobic, Parasitic |
 |
Grows on |
Eastern Hemlocks
|
 |
Distribution | Northeastern North America |
 |
Cap |
Fan-shaped/Kidney-shaped • Up to 30 cm across • Lacquered, furrowed • Red, with yellow and white margin when young
|
 |
Hymenium | Pores • White |
 |
Stipe |
Central
• 2.5-15 cm • 3 cm thick
3 cm
• Red and varnished
|
 |
Flesh |
White, softwhen young; corky when old
|
 |
Odor & Taste | Not distinctive |
 |
Spore Print | Brown |
Research Sources
1 Laetiporus sulphureus by Gary Emberger, Messiah College, 2008.
2 Ganoderma tsugae by Michael Kuo, MushroomExpert.com, January 2019.
3 Ganoderma tsugae Murrill, Bull. Torrey bot. Club 29: 601 (1902), Index Fungorum, Retrieved July 2022.
4 National Audubon Society Field Guide to Mushrooms by Gary Lincoff, Chanticleer Press, 1981.
5 Ganoderma tsugae by Michael Kuo, MushroomExpert.com, January 2019.
6 Genome of Ganoderma Species Provides Insights Into the Evolution, Conifers Substrate Utilization, and Terpene Synthesis for Ganoderma tsugae by Nan Jiang, Shuang Hu, Bing Peng, Zhenhao Li, Xiaohui Yuan, Shijun Xiao and Yongping Fu, Frontiers of Microbiology, 16 September 2021.
7 Ganoderma curtisii. Photo 209121663, (c) lrobinsonti, some rights reserved (CC BY-NC), uploaded by lrobinsonti. Minor color edits made.
8 Ganoderma oregononse, Photo 197678022, (c) Braden J. Judson, some rights reserved (CC BY-NC), uploaded by Braden J. Judson. Minor color edits and extension of background.
Don't miss out
Grab some mushy merchandise!