Macro Mushroom (Agaricus urinascens) Identification

Macro Mushroom / Autumn / Edible

Scientific Name

Agaricus urinascens

Common Names

Macro Mushroom




In fields, meadows and parks. They are saprotrophic, feeding on the dead roots systems of grasses and moss. They can appear individually or in small groups.


A rare find in the UK, they have undergone some names changes over the years so you may see it listed as Agaricus macrosporus or Agaricus crocodilinus. To make things even more confusing there is also a woodland variant Agaricus urinascens var, excellens but this is very, very rare.

Identifying Features:


When young the cap is smooth, as it grows they flatten out, darken slightly and develop rough scales, often splitting at their edges.

gailhampshire from Cradley, Malvern, U.K, CC BY 2.0 <>, via Wikimedia Commons


The stems are white and have a delicate skirt. The stem is smooth above the skirt and scaly below. Quite stout. Around 7-12 cm long and when cut it will stain slightly reddish-brown.

© Traumrune / Wikimedia Commons


The gills are crowded and free, pink initially they darken to a rich brown colour when mature.

Strobilomyces, CC BY-SA 3.0 <>, via Wikimedia Commons
Free Gills


When young they have a pleasant almond scent but as they mature they smell increasingly of urine.




In food

A really tasty mushroom, they can be used in lots of ways and can be used in the same way as Portobello mushrooms


The younger caps are best as they can get a bit maggoty as they get older depending on how squeamish you are.

This image was created by user I. G. Safonov (IGSafonov) at Mushroom Observer, a source for mycological images.You can contact this user here.English | español | français | italiano | македонски | മലയാളം | português | +/−, CC BY-SA 3.0 <>, via Wikimedia Commons

Known hazards

None Known.

Potential lookalikes

The young specimens have been mistaken for Amanita species in the past, so inexperienced foragers should only collect more mature examples who’s gills have darkened, as the gills of Amanitas stay white.

It could be confused with other Agarics the main one to be wary of is The Yellow Stainer (Agaricus xanthodermus) it can looks similar but stains bright yellow when damaged and smells of iodine.

Extra Notes

The name urinascens comes from Latin and means ‘gradually acquiring a smell like urine’, the common English name Macro refers to their huge size.

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