About this fungus
Blue Meanies (Panaeolus) is a fungus in the Galeropsidaceae family. Its habitat and field characteristics are summarised below.
A fragile, long-stemmed mushroom of dung and heavily manured ground. Fresh caps are pale brown or grey-brown and often fade towards whitish grey, while handling or weather damage can produce conspicuous blue or blue-green marks. Turn one over and the pale cap contrasts with patchy grey-black gills and a very slender, ringless stem.
What to check
Check the full combination rather than blue staining alone. The cap is usually rounded, bell-shaped or broadly conical when young and may expand towards convex. Its surface is smooth and can crack in dry weather. Gills meet the stem narrowly or broadly and mature unevenly, producing the mottled dark-and-light pattern typical of Panaeolus; their faces become grey to black while the edges often remain pale. The spore print is black. Cap and stem tissue can bruise blue or blue-green, especially at damaged stem bases. There is no persistent ring and no volva.
Variation
Moist young caps may be light brown or grey-brown with a warmer centre, then fade through grey to cream or nearly white as they dry. Blue staining ranges from quick and dark to patchy or subtle, so its absence in one untouched photograph is not decisive. Gills can look pale grey in immature specimens, strongly mottled while spores mature and almost black when old. The fruit bodies are delicate, and collapsed stems or dark handling marks can obscure useful characters.
Lookalikes
Panaeolus tropicalis, P. cambodginiensis, P. bisporus and other blue-staining members of the same group can be extremely similar and may require spore, cystidium or DNA evidence. Panaeolus antillarum also grows on dung and has a black print but is usually larger and more robust and does not normally stain blue. Other non-blueing mottlegills can share the black, patchy gills. Psilocybe cubensis is usually larger, has a veil that leaves a ring and gives a dark purple-brown rather than truly black print. The earlier draft's Galerina marginata and Pholiotina rugosa comparison was not a good primary match because those mushrooms have rusty-brown spores and different usual substrates and structures.
Habitat and range
Saprotrophic on cattle, horse and other herbivore dung, or on soil and grass strongly enriched with manure. It occurs mainly in tropical and subtropical pastures, grassland and gardens and often fruits after warm rain. Records extend through parts of Africa, Asia, Australia, the Pacific and the Americas, so the old name The Hawaiian gives a misleadingly narrow impression of its range. Similar species occur beside it in some regions, making local microscopy and DNA records especially useful.
Food safety
Psychoactive.