Lactarius argillaceifolius var. megacarpus
Cap 9-21 cm broad, convex-depressed, the margin incurved, often wavy; surface viscid when moist, smooth, obscurely zonate, buff-brown, light grey-brown, sometimes spotted or mottled darker brown, at times tinged lilac, typically lighter at maturity; flesh thick, pallid to cream, unchanging; odor indistinct; taste mildly peppery.
Gills subdecurrent, moderately broad, close to crowded, cream becoming dingy-buff in age; latex white unchanging but discoloring gill tissue grey-brown.
Stipe 7-14 cm tall, 2-5 cm thick, stout, stuffed, more or less equal; surface subviscid to dry, cream, irregularly pale-buff in age; flesh white unchanging; veil absent.
Spores 7-9 µm, round to subglobose with partially reticulate amyloid ornamentation; spore print cream-yellow.
Solitary to scattered under oaks, especially coast live oak (Quercus agrifolia); fruiting from mid to late winter.
Large size and drab coloration characterize Lactarius argillaceifolius var. megacarpus. Lactarius pallescens is similar though usually paler colored, smaller, with a latex that stains gill tissue lilac, not grey-brown. The largest of our local milky caps, Lactarius argillaceifolius var. megacarpus can be common in some years and rare in others.