Description in Keys to the Species of Russula in Northeastern North Americaby Kibby & Fatto, 3rd Edition, 1990:
Cap 5-15 cm, soon infundibuliform, dry, felty, chalky-white, then soon dull brown to blakc, margin even, not peeling. Gills close to subdistant, adnate to short-decurrent, ivory-yellow to buff, then dingy gray-buff. Lamellulae abundant. Stem short, stout, very firm, white then brownish-black. Flesh white, when wounded, turning strongly reddish before turning black. Odor slight. Taste mild to slightly acrid, sometimes burning acrid. Spore print white (A). Spores 7.5-11 × 6.5-9 microns; warts 0.1-0.5 micron; reticulate. No pleurocystidia. This species was called R. nigricans for a long time before being distinguished by Shaffer. It differs in its closer gills, larger spores with higher warts and non-viscid caps. Found in coniferous and mixed woods.