Agaricus sapineus Fries (1815) Gymnopilus sapineus, commonly known as the scaly rustgill or common and boring gymnopilus,[2] is a small and widely distributed mushroom which grows in dense clusters on dead conifer wood.

[3] This is further complicated by the macroscopic morphological and ecological similarities between members of the G. sapineus complex such as G. penetrans and G. nevadensis.

This mushroom is often mistaken for G. luteocarneus which grows on conifers and has a smoother and darker cap.

The cap margin is inrolled at first and curves outward as it matures, becoming almost plane and sometimes developing fibrillose cracks in age.

[5] The flesh is yellow[5] to orange and delicate when compared to larger and firmer members of Gymnopilus, such as G. junonius.