Glistening inkcapCoprinellus micaceus

The glistening inkcap (Coprinellus micaceus), known in North America as the mica cap, is one of the commonest mushrooms in towns. Small, honey-brown, grooved caps grow in dense tufts by stumps, and young ones look as if they've been dusted with sugar or glitter. Those white grains are remnants of the veil, and rain soon washes them off. Like other inkcaps, the mature mushroom blackens and partly dissolves into ink.

How do you identify a glistening inkcap? The cap is 2 to 4 cm across, occasionally 5 cm, egg-shaped at first, then bell-shaped, honey brown to ochre with a russet centre and a paler margin, and grooved almost to the top. The glittering grains on young caps are the best clue, but they may be gone after rain. The gills are crowded, white at first, then grey-brown and black. The stem is white, silky, hollow and brittle, 3 to 8 cm tall, with no ring. The spore print is black-brown to black.

Where does it grow? On rotting broadleaved wood: stumps, roots and buried wood, so it can seem to sprout straight from a lawn. It's very common in towns, around street trees, in parks, gardens and car-park edges. It can appear in any month in mild weather, but mostly from spring to early winter, with the biggest flush in mid-autumn. The same stump can fruit several times a season.

Is the glistening inkcap edible? It's edible when young and fresh, though small, thin-fleshed and not highly rated, and some sources call it inedible for that reason. It starts to blacken within hours of picking, so cook it straight away. The German Mycological Society lists it among the inkcaps that can react with alcohol, noting that it contains only small amounts of coprine, while other sources find no coprine at all, so avoid alcohol for a few days before and after eating it, as a reaction is possible for several days. Avoid roadside and contaminated sites, as it can take up lead and cadmium. There's no evidence that it's psychedelic. If anyone feels unwell after eating it, especially with a drink (flushing, a racing heart, nausea), call emergency services on 112 (999 in the UK) or your local poison centre. And if other little brown mushrooms from a stump might have been in the meal and vomiting or diarrhoea starts 6 to 24 hours later, call 112 (999 in the UK) straight away, even if it then seems to ease.

What can you mistake it for? The common inkcap is larger and grey, with no glitter, and must never be eaten with alcohol. The shaggy inkcap is tall, white and shaggy and grows in grass. Its closest relatives, the willow inkcap and Coprinellus saccharinus, can only be separated under a microscope and aren't known to be dangerous. The fairy inkcap is far smaller and grows in troops of hundreds, and the firerug inkcap sits on an orange woolly mat. The real risk is picking other little brown mushrooms from the same stump once the glitter has washed off. The common stump brittlestem has a white veil fringe on the cap edge and doesn't dissolve. Sheathed woodtuft and the deadly funeral bell both have a ring or ring zone and a brown spore print, and neither turns to ink, but they can often only be told apart from each other under a microscope, so don't pick little brown mushrooms from stumps without experience, and never mix inkcaps with them in one basket. Mica cap vs liberty cap? The liberty cap grows scattered in grass, has a pointed tip and a purple-brown spore print, and never grows in dense tufts on wood.

Its name micaceus means "like mica", after those glittering grains. Each fruit body lasts only a few days.