Ecology: Mycorrhizal with hardwoods (especially oaks); also sometimes reported under conifers; growing alone, scattered, or gregariously; summer and fall; widely distributed east of the Great Plains, and extending at least as far south as Costa Rica.
Cap: 3-10.5 cm; convex with a small point in the middle, becoming flat with an uplifted margin, with the central point often disappearing; dry; usually described as finely velvety (but see comments above); often with a rugged and wrinkled surface; yellow-brown to grayish brown; the margin sometimes becoming scalloped.
Gills: Running down the stem; quite distant; stark white.
Stem: 3-8 cm long; 1-2.5 cm thick; more or less equal; dry; without potholes; textured and colored like the cap; sometimes with a white apex, or sometimes with the gills running into the brown coloration; becoming hollow.
Flesh: White; thin; somewhat brittle.
Milk: White; unchanging on exposure to air; not staining tissues.
Odor and Taste: Odor not distinctive; taste mild or slightly acrid.
Chemical Reactions: KOH on cap surface negative; on flesh yellowish.
Spore Print: White.
Microscopic Features: Spores 7-10 × 7.5-9 µ; globose to subglobose; ornamentation 0.5-0.8 µ high, as amyloid warts and ridges forming partial or complete reticula. Pleuromacrocystidia absent, or present as scattered clavate elements slightly projecting. Cheilocystidia inconspicuous; cylindric. Pileipellis a trichoepithelium; terminal cells long and cystidium-like; brown in KOH.
REFERENCES: Peck, 1873, (Saccardo, 1887; Coker, 1918; Hesler & Smith, 1979; Smith, Smith & Weber, 1979; Phillips, 1991/2005; Lincoff, 1992; Roody, 2003; McNeil, 2006; Binion et al., 2008.) Herb. Kuo 08050305, 07230406, 07160705, 06280805.
Kuo, M. (2011, March). Lactarius gerardii. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/lactarius_gerardii.html