Velvety milk cap

Appearance

The cap of ''L. fallax'' is 3–9 cm wide, ranging in shape from convex to nearly flat with a small umbo, expanding to plane or becoming shallowly depressed, with or without the umbo. The margin is even or scalloped. The cap surface is dry and velvety, finely wrinkled over the center, azonate , and dark sooty brown to blackish. The gills are attached to subdecurrent , narrow, crowded, not forked, white at first, and become creamy buff with age. The edges of the gills are brown like the cap, and slowly stain vinaceous when bruised. There are several tiers of lamellulae interspersed among the full-length gills. The stem is 2.5–6 cm long, 8–15 mm thick, nearly equal in width throughout, dry, solid, unpolished or velvety, and a paler brown than the cap. The flesh is thin, brittle, staining pale vinaceous. The odor is not distinctive, and the taste mild or faintly acrid. The latex is copious, white on exposure, unchanging, slowly staining flesh and gills vinaceous. The spore print is yellowish. The edibility of the mushroom has not been officially documented. The species is one of several brown to nearly black milkcaps that are, according to David Arora, "notable for their beauty, and therefore likely to attract the attention of even the casual collector."

The variety ''Lactarius fallax'' var. ''concolor'' is nearly identical to the main species in appearance and distribution, but has gill edges that are colored like the gill face.The spores are spherical, and ornamented with warts and ridges that form a partial reticulum with prominences up to 2 µm high. They are hyaline , amyloid , and measure 7.5–10.0 by 7–9.5 µm. The cap cuticle is a trichoderm. The basidia are 38–56 by 10–13 µm, club-shaped, four-spored, and hyaline when mounted in a dilute solution of potassium hydroxide . There are abundant cheilocystidia , with contents ranging in color from dingy yellow to hyaline in KOH. They measure 32–50 by 3-6 µm, and may be shaped somewhat like a spindle or a cylinder, or they may be flexuous . The pleurocystidia are filamentous, 2.5–5 µm in diameter, and rare to scattered.

Naming

''Lactarius lignyotellus'' and ''L. lignyotus'' are similar to ''L. fallax'', and they are all associated with ''Picea'' and ''Abies''; examination of microscopic features cannot be used to distinguish between them. ''L. lignyotus'' is restricted in distribution to eastern North America and Europe. ''Lactarius pseudomucidus'' is another milk cap with a dark brown cap, but it has a smooth and slimy cap and stem. Another brown-capped eastern North American species is ''L. gerardii''; it has distantly spaced white gills that run down the stem. ''L. fuliginellus'', which prefers to grow near hardwoods, has close gills.

Distribution

The fruit bodies of ''L. fallax'' grow scattered to grouped together on the ground, or on very rotten conifer logs in alpine areas under standing conifers. They are fairly common, and typically found between August and October. ''L. fallax'' is distributed in the western United States and Canada, with the northern range extending to Alaska; the eastern range is bounded on the east by the Great Plains. Field observations suggest that the fungus can form ectomycorrhizal associations with ''Tsuga heterophylla''. Hesler and Smith noted that the variety ''concolor'' was prevalent under species of Fir.