About Agaricus subrutilescens (Kauffman) Hotson & D.E.Stuntz
Agaricus subrutilescens has a cap measuring 5–15 cm (2–6 in) across; the cap surface is dry and covered with numerous wine-colored to brown fibrils, which are most concentrated near the cap center. The gills are closely spaced: they start out white, turn pinkish as they mature, and become dark brown when the mushroom ages. The stalk is 4 to 20 cm (1+5⁄8 to 7+7⁄8 in) long, 1–3 cm (3⁄8–1+1⁄8 in) thick, white, and bears a skirt-like ring. Below the ring, the stalk is covered in soft, woolly scales. The mushroom's flesh is white and does not change color when cut or bruised, and it has a mild odor and taste. The combination of a purplish fibrous cap and shaggy white stem distinguishes this species from other similar-looking mushrooms. Known similar species include Agaricus hondensis and Agaricus moelleri.
This species fruits in undisturbed mixed woodlands in Western North America and Japan. It grows either singly or scattered in small clusters, and is often found growing under redwood, pine, or alder trees. It has recently been newly identified in New Zealand and Australia.