''Gymnopilus junonius'' is a species of mushroom-forming fungus in the family Hymenogastraceae. Commonly known as the spectacular rustgill, this large orange mushroom is typically found growing on tree stumps, logs, or tree bases. Some

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

of this mushroom contain the neurotoxic oligoisoprenoid gymnopilin.

Description

The cap ranges from across, is convex to flat, and is bright yellow-orange in younger specimens and orange-brown or reddish brown in older ones, with a dry scaly surface. The flesh is yellow, the odor mild and taste bitter. The

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...

is long, 1–5 cm thick, and often narrows near the base. The frail ring is dusted with rusty orange spores, and the gill attachment to the stem is adnate to sub-decurrent. It stains red with KOH and turns green when cooked. The spore print is rusty orange. Unlike psychoactive relatives in the '' Psilocybe'' genus, ''G. junonius'' lacks psilocybin and does not stain blue, but smaller specimens occasionally exhibit bruising. This mushroom usually grows in clusters from several to several dozen individuals, but sometimes grows solitary. It is inedible due to its bitter taste. Gymnopilus junonius

Similar species

This mushroom is often mistaken for ''

Gymnopilus ventricosus ''Gymnopilus ventricosus'' is a species of mushroom in the family Hymenogastraceae. It was first described from the Stanford University campus by Franklin Sumner Earle as ''Pholiota ventricosa'' in 1902. Description The cap is or larger in ...

'', which also contains no psilocybin and ''G. luteus'' and ''G. subspectabilis'', which do. It also resembles '' Armillaria mellea'' and '' Omphalotus olivascens''.

Distribution and habitat

''Gymnopilus junonius'' is found in Europe, Australasia and South America. It grows in dense clusters on stumps and logs of hardwoods and conifers. This mushroom is most common in moist, lowland wooded areas near rivers. This species does not occur in North America; however some similar looking species do. These include ''

'' on the west coast and ''G. luteus'' and ''G. subspectabilis'' in the midwest and east.

Biochemistry

This mushroom contains bis-noryangonin and hispidin, which are structurally related to alpha-pyrones found in

kava Kava or kava kava (''Piper methysticum'': Latin 'pepper' and Latinized Greek 'intoxicating') is a crop of the Pacific Islands. The name ''kava'' is from Tongan and Marquesan, meaning 'bitter'; other names for kava include ''ʻawa'' (Hawaiʻi), ...

. Neurotoxins known as oligoisoprenoids have also been found in this species.

References

*C.J. Alexopolous, Charles W. Mims, M. Blackwell et al., ''Introductory Mycology, 4th ed.'' (John Wiley and Sons, Hoboken NJ, 2004)

External links