Agaricus decastes Fr.
Cap (Pileus): 0.6 – 7.0 cm broad; conic to ovoid at first, then acutely convex and bell shaped, occasionally shallowly convex with a pointed centre; margins even and incurved at first, then decurved and finally straight and flaring, often exceeding the gills; surface moist, polished, usually smooth but other times with minute flattened scales on the centre and with fibrils towards the margins, at times with shallow grooves and pits; colour when young evenly dark brown on centre, fading to lighter brown towards margins, when mature becoming grey black, scales when present grey black; context 1 cm at junction of the stipe, moist and watery, solid, pale to grey brown, whitish towards the junction of the stipe, no colour change when bruised; taste cucumber-like; odour cucumber-like.
Gills or Lamellae (Hymenium): horizontal; spaced average to crowded; edges even, at times wavy; thick, 0.5 cm broad, at times broader in the middle; colour white to grey occasionally yellowing to browning when bruised; multiple tiered with short gills.
Stalk (Stipe): 1.2 – 8.0 cm long X 1.0 – 2.0 cm wide at apex, 1.8 – 2.0 cm wide at middle, 1.2 – 2.0 cm wide at base; bottle shaped; surface moist, fibrous, striate, at times powdery at apex, at times with scales, with fibrils peeling down stalk; colour white to ivory with some yellow brown towards base; context solid, spongy and white.
Spore print white; spores 6 – 7 X 6 – 8 µm, globose to subglobose, smooth, inamyloid; no apparent hymenial cystidia; hyphae with clamp connections.
Comments: The taxonomic position of the Lyophyllum decastes group is uncertain. The genus Lyophyllum was previously recognized microscopically by the presence of siderophilous granules in the basidia. However, it is now recognized that this feature is not definitive, as other genera also possess them. Genetic and cultural research has shown that for some mushrooms, cultural and ecological characters are more helpful for classifying them to genus and species than morphology. This may be the case for the Lyophyllum decastes group. Morphological, cultural, enzymatic and DNA analysis suggests that there are 5 distinct species in this species complex. Consequently, both taxonomy and nomenclature are currently being revised both in the L. decastes group and in the genus as a whole.
Based on overall appearance, the soil-inhabiting Lyophyllum decastes can be confused with the wood-inhabiting Hypsizygus tessulatus and Gymnopus acervatus (= Collybia acervata). Individual fruiting bodies of Gymnopus acervatus, which fruit in tight “heaps”, are smaller and have reddish or pinkish tones to the cap and stalk and close to crowded almost-free gills. Hypsizygus tessulatus, which causes brown rot in deciduous trees, has a tough texture (not fleshy like L. decastes), and lacks carminophilous granulations in the basidia. The Honey Mushroom, Armillaria ostoyae, which is a variable mushroom that fruits either on wood or in soil, differs from L. decastes by having a well-developed ring around the stipe and large scales on the cap that can easily wash off over time. The poisonous Clitocybe connata (=Clitocybe dilatata) is also found on roadsides and among grasses, but differs from L. decastes in being white to whitish buff and having decurrent gills and ellipsoidal spores. Lyophyllum decastes has a greyish to brown cap, horizontal gills and round spores. The smaller Pholiota terrestris, which also fruits in clusters on the ground along roads, has brown spores and a stipe and cap with large scales. The edible fairy ring mushroom, Marasmius oreades, which also occurs in lawns and has white spores, is distinguished by its reddish brown cap colours and its habit of fruiting scattered in gregarious troops or rings rather than in closely packed clusters.
Habit, Ecology, Habitat and Range
The Lyophyllum decastes group produces fruiting bodies that are fused at the base to form clusters or tufts. This group was previously thought to be saprophytic, but there are reports that it can form mycorrhizae with coniferous and deciduous trees. This common mushroom is always found on the ground on disturbed sites such as old logging roads or in grasses, lawns and meadows throughout the province. It usually fruits from mid August to late November, but occasionally it is found in the spring. This mushroom has been collected on Vancouver Island, the southern coast, Squamish area, the Robson Valley, the north west and the northern coast.
When cooked, this mushroom is said to taste like fried chicken, though some disagree - thus its common name. Lyophyllum decastes is popular in Japan, the United Kingdom and Northern Europe. Members of the Danish mycological society voted this species as one of the most delicious mushrooms. This species has high amounts of vitamins, but low amounts of proteins, sugars and minerals compared to other mushrooms.
Researchers report that rats fed Lyophylum decastes have significant lower cholesterol, serum triglycerides and phospholipids and higher than rats that had not consumed the mushroom. Compounds that can inhibit cancer tumors in mice and also protect their cells from radiation have been isolated from L. decastes. These compounds can protect total development when mice are radiated.
Although many people eat Lyophyllum decastes, there have been some reports of violent gastrointestinal attacks attributed to this mushroom. The North American Mycological Association poisoning registry reported that people have become dizzy and nauseated, have vomited and had diarrhea after eating this mushroom. The variation in symptoms could be due to the variability and complexity of the species group and the difficulty in identifying specimens.
In Japan, this mushroom is used in bioremediation of toxic sites and water purification systems. It is cultivated on wastes after cultivating Pleurotus ostreatus and Pholiota nameko. Many patents have been granted for cultivation techniques of L. decastes in Japan.
Agerer, R., and L. Beenken. 1998. Lyophyllum decastes (Fr.) Sing. + Quercus robur L. Descriptions of Ectomycorrhizae 3: 43-47.
Akamatsu, Y. 1998. Reutilization of culture wastes of Pleurotus ostreatus and Pholiota nameko for cultivation of Lyophyllum decastes. Journal of Wood Science 44: 417-420.
Gu Y., Y. Ukawa, I. Suzuki, S. Park, and T. Iwasa. 2001. The study of anticancer effect and radiation protection effect to the Hatakeshimeji (Lyophyllum decastes (Fr.) Sing.) on radiation influence. International Conference on Medicinal Mushrooms. Kiev. Ukraine. Abstracts.
Hofstetter, V., H. Clémençon, R. Vilgalys, and J.M. Moncalvo. 2002. Phylogenetic analyses of the Lyophylleae (Agaricales, Basidiomycota) based on nuclear and mitochondrial rDNA sequences. Mycological Research 106: 1043-1059.
Kinuta, M., T. Furuno, A. Takahashi, and I. Furukawa. 1995. Ecology and wood decay of Lyophyllum decastes. Journal of Wood Research 41: 511-515.
Moncalvo, J.M., and H. Clémençon. 1994. Enzymatic studies as an aid to the taxonomy of the Lyophyllum decastes complex. Mycological Research 98: 375-383.
Moncalvo, J.M., S.A. Rehner, and R. Vilgalys. 1993. Systematics of Lyophyllum Section Difformia based on evidence from culture studies and riobosomal DNA sequences. Mycologia 85: 788-794.
Moncalvo, J.M., and H. Clémençon. 1992. A comparative study of fruit body morphology and culture characters in the Lyophyllum decastes complex (Agaricales, Basidiomycetes) from Japan and Europe. Transactions of the Mycological Society of Japan 33: 3-11.
Ukawa, Y., Y. Furuichi, Y. Kokean, T. Nishii, and M. Hisamatsu. 2002. Effect of hatakeshimeji (Lyophyllum decastes Sing.) mushroom on serum lipid levels in rats. Journal of Nutritional Science and Vitaminology 48: 73 – 76.
