Cap 4-11 cm broad, convex, broadly convex to nearly plane in age, the disc often depressed; margin incurved, then decurved at maturity; surface subviscid when moist, glabrous, faintly zonate with alternating bands of pinkish-brown, reddish-brown, and orange-brown, often dotted with darker spots; context 0.5-1.0 cm thick at the disc, thin at the margin, cream-colored, yellowing quickly when injured; odor, mild; taste usually peppery.
Gills adnate to subdecurrent, moderately broad, close, brittle, at first pale peach-buff, then orange-buff, bleeding a white, soon yellow latex.
Stipe 3-6 cm tall, 1-2 cm thick, brittle, solid near the base, hollow at the apex, equal to slightly enlarged at the base; surface moist, glabrous, not pitted (scrobiculate), peach-buff to pale, pinkish-brown, the base with pallid to dingy-buff hairs; cortical flesh exuding a white, soon yellow latex when injured; veil absent.
Spores 7-8 x 6-6.5 µm, subglobose to broadly ellipsoid, partially reticulate, ornamentation amyloid; spore print pale yellow.
Scattered in hardwood/conifer woods; fruiting from early to mid-winter.
Toxic, can cause severe gastrointestinal upset. The peppery taste should serve as a deterrent.
Lactarius xanthogalactus is recognized by a reddish-brown to pinkish-brown, inconspicuously zoned cap and white, changing to yellow latex. Additional field characters are the lack of a bearded cap margin and scrobiculations on the stipe. For many years Bay Area mycophiles were uncertain what was the correct name for this mushroom, it having been known also as Lactarius chrysorheus and L. vinaceorufescens. Fortunately this and related taxonomic problems were addressed in a recent California monograph of the genus by Andrew Methven. He concluded that local material best fits Peck's description for Lactarius xanthogalactus and that Lactarius chrysorheus and L. vinaceorufescens, while good species in their own right, occurred only in the Eastern U.S.
Inexperienced collectors might confuse Lactarius xanthogalactus with Lactarius rubidus, another red-brown capped species, but the latter has an evenly colored (not zonate) cap, a watery latex and a sweet odor, especially when dried. Less common in our area is Lactarius rufus, an evenly colored red-brown species with a white, unchanging latex, and an exceedingly peppery taste.