Cultivated Mushroom Agaricus bisporus (J.E. Lange) Imbach (illustrated 50% life size) Cap 5–10cm across, hemispherical expanding convex; greyish-brown to umber, covered in brown radiating fibres; often slightly scaly with age. Stem 35–55×8–14mm; white; often flaky below the membranous, sheathing ring. Flesh white, bruising faintly red; taste and smell mushroomy. Gills free; dirty pinkish, darkening with age. Spores 4–7.5×4–5.5¼, ovate to subglobose. Spore print brown. Basidia 2-spored, separating this species from the rest of the genus, which all have 4-spored basidia. Cheilocystidia 17–44×7–14¼, elongate-clavate, thin-walled. Habitat on manure heaps, garden waste, and roadsides, not in grass; late spring to autumn. Occasional. Edible. Note this species is believed to be the wild form of many of the cultivated crop varieties, all of which have 2-spored basidia.