"Reishi" is an umbrella term that describes many mushrooms in the Ganoderma genus, and guess what? They're medicinal!
Ganoderma curtisii "Yellow Reishi" Lithia Springs, FL 12/21
The most well-known Reishi mushroom is the Chinese Ganoderma lucidum, or "Lingzhi" mushroom that has been used in traditional Chinese medicine for centuries. The latin name "Ganoderma" breaks down as "Gano" meaning shiny, and "derma" meaning skin. These mushrooms, especially the well-known "Lingzhi," are recognized by their varnished appearance.
In North America our most polished-looking species would be the "Hemlock Varnish Shelf." We actually haven't encountered this specific species in our explorations yet but these mushrooms tend to grow on Hemlock trees in the eastern part of North America.
In North America we have medicinal Reishi species including:
Ganoderma tsugae "Hemlock Varnish Shelf"
Ganoderma sessile "Reishi"
Ganoderma curtisii "Yellow Reish"
Ganoderma appalantum (complex) "Artist's Conk"
We're currently traveling along the Atlantic coast of Florida, and therefore we're encountering the "Yellow Reishi" most frequently, as this species favors the south eastern region of North America. The latin name G. sessile refers to the fact that this species most often does not contain a stalk or stipe.
Below is a gallery of different species of Ganodmera we've spotted in our travels:
As far as the medicinal properties, Reishi mushrooms contain polysaccharides that have been known to help fight cancer and reduce tumor size (similar to Lion's Mane and Turkey Tail mushrooms). According to the studies of the Memorial Sloan Kettering Cancer Center out of New York City,
"Extracts of reishi were shown to have immunomodulatory (2) (4) (5), renoprotective (9), anti-inflammatory (36), and hepatoprotective (37) properties both in vitro and in vivo. Clinical studies indicate its benefits in improving lower urinary tract symptoms (LUTS) in men (10) (20), and in exerting mild antidiabetic effects and improving dyslipidemia (29). [...] Reishi has also been studied for its anticancer potential. Preclinical findings indicate that it has immunomodulatory (45) and chemopreventive effects (21) (46), alleviates chemotherapy-induced nausea (13), enhances the efficacy of radiotherapy (22), and increases sensitivity of ovarian cancer cells to cisplatin (27).[...] In small clinical studies, reishi increased plasma antioxidant capacity (6) (7), enhanced both immune and tumor response in cancer patients (8) (40) (44), [...] and a formula containing reishi and ligustrum helped maintain the quality of life in non-small cell lung cancer patients undergoing chemotherapy (48)."
Western medical attention and research into mycology is still very "new" so to speak; therefore, more clinical studies by a wide range of institutions are necessary before "Reishi" mushrooms can be used as official treatments for disease or ailments.
For now? We like to forage these mushrooms, dehydrate them, and grind them into a powder to make them into a tea or tincture.
Haritan, Adam "Foraging Wild Mushrooms Online Course"