Agaricus julius

Agaricus julius, commonly known as the emperor or the prince, is a basidiomycete fungus of the genus Agaricus, closely related to Agaricus augustus.

Agaricus julius was first described by American mycologist Richard W. Kerrigan in 2016.^[2]

The cap is 5–15 cm (2–6 in) wide, sometimes larger. The appearance of this mushroom is very similar to the store-bought portobello mushroom. It stains slightly yellow where damaged or nicked. The cap is light brown with a scaled pattern. When young, it has a cottony veil covering the gills. The mushroom can become quite large as the cap opens. The gills are initially pinkish-gray to pink when young, then turning brown at maturity; crowded; not attached to the stipe.

The stipe is 2–3 cm (3⁄4–1+1⁄4 in) wide, and 5–15 cm (2–6 in) long. The stalk is usually shaggy when young, becoming smooth at maturity, curved with a larger bulbous base. Once the cap opens it leaves a thin yellowish to light brown skirt-like ring on the stipe. When mature, the stalk can turn darker above the ring. The cap flesh can stain yellow in fresh specimens where nicked or handled. It has a very distinct cherry-almond smell. The spore color is chocolate brown.^[3]

In March 2025, the fungus became the state mushroom of Colorado.^[4]