CAP: (6-14 cm) wide, convex, becoming flat in age; surface dry, smooth, not velvety and not sticky or slimy, often becoming cracked in age, dull rusty brown to dull reddish brown, fading to dull cinnamon or dingy yellow-brown; cap surface staining blue, then dull purplish with NH₄OH; cracks, if present, showing yellow flesh; flesh bright yellow, staining quickly blue when cut or bruised; odor and taste not distinctive.

PORE SURFACE: yellow to ochre-yellow when young, olive-ochre in age, rapidly staining blue, then changing to brown when bruised; pores circular to angular, 1-3 per mm.

STALK: (8-16 cm) long, (1.5-3 cm) thick, equal or flared slightly at the apex, solid, typically yellow at the apex and flushed rusty red, pinkish, or purplish below, not reticulate; partial veil and ring absent.

SPORE PRINT: olive-brown.

MICROSCOPIC FEATURES: spores 9-12 x 3-4 μm; subfusiform to oblong, smooth, pale brown.

FRUITING: gregarious on the ground in hardwoods, especially under oak; July-September; occasional.

EDIBILITY: edible, but not recommended because of possible confusion with similar-appearing poisonous species.

From Mushrooms of Northeastern North America Alan E. Bessette, Arleen R. Bessette, & David W. Fischer  Copright © 1997 Syracuse University, ISBN 0-8156-0388-6