- cap is blue, up to 15cm wide, convex with an inrolled margin.
- older specimens are greyish-blue with a depression in the cap.
- flesh is indigo colored, staining green.
- cutting across the gills releases a dark indigo latex which turns green.
- gills are light blue and descend shortly down the stem.
- stem is indigo/blue and hollow.
- grows under conifer and hardwood stands.
- appears in late sumer or fall.
- taste is mildly bitter or neutral, with no odor; cook before eating.
- edible lookalike is Lactarius paradoxus, which has lightly orange gills which release a red latex when cut.