Lactarius atroviridis has a rugose blackish-green convex cap with vaguely concentric scrobiculations, especially along the inrolled margin. As the cap expands, the central disc becomes depressed. Attached gills are close, white, often forked and of varying lengths. They bruise and stain greenish with age. The spore print is cream. The latex is white and acrid and sometimes turns greenish on exposure. The stipe is concolorous with the cap and scrobiculate. Taste is mild to acrid. It is found in mixed woods, especially with oaks in summer and fall.