What You Should Know
Lactarius quietus is a mushroom of the genus Lactarius. It is easily identified by its oily scent and the concentric bands on its cap. It is found exclusively under oak trees in Europe, where it grows solitarily or in scattered groups in autumn months. In North America, the variety L. quietus var. incanus is fairly common in the same habitat. It is edible, though is not to everyone’s taste, and is said to have an oily smell, similar to bed bugs.
It is thought that milkcap fungi (Lactarius spp.) exude latex as a form of self-defense when damaged because it dries to form a protective coating around the injury, keeping out bacteria and other contaminants.
Other names: Oakbug Milkcap, Oak Milkcap, Southern Milkcap.
Lactarius quietus Mushroom Identification
Mycorrhizal with oaks, and perhaps with other hardwoods in oak-based forests; growing alone, scattered, or gregariously; summer and fall; widely distributed in eastern North America.
3-11 cm; convex, becoming flat or shallowly vase-shaped; dry; smooth or uneven and somewhat rugged; when young often with a whitish dusting; usually zoned with shades of dark reddish-brown, but sometimes becoming vaguely zoned or without zones - or becoming less zoned with age.
Attached to the stem or running slightly down it; close or nearly crowded; whitish at first, developing cinnamon stains and discolorations, but not staining from the milk.
4-14 cm long; up to 1.5 cm thick; more or less equal; smooth; without potholes; when young with a white dusting; colored like the cap, but paler; darkening with age from the base upward; hollowing.
Whitish to pinkish; not changing when sliced, or staining slowly pinkish.
White at first, becoming watery with age; sometimes slightly yellowish; not changing on exposure; not staining tissues; often staining white paper yellow overnight.
Odor and Taste
Odor strongly fragrant, or not distinctive; taste mild or slightly acrid.
KOH olive on cap surface.
White or pale yellowish.
Spores 6-8 x 5-7 µ; broadly ellipsoid; ornamentation 0.5-1.0 µ high, as amyloid warts and scattered ridges that occasionally form zebroid patterns but do not form reticula. Pleuromacrocystidia scattered to abundant; fusoid; to about 70 x 10 µ. Cheilocystidia scattered to abundant; fusoid; to about 40 µ long. Pileipellis a trichoderm or oedotrichoderm.
Lactarius quietus Look-Alikes
Larger and darker and usually has a central umbo; it occurs under conifers and occasionally birch and releases a bitter latex when the gills are damaged.
Lactarius quietus var. incanus
Typically slightly larger than the nominate variety, and younger specimens feature a whitish bloom, after which the variant is named. It has a sweet smell reminiscent of maple syrup and can be commonly found under oak trees. It can be confused with L. aquifluus and L. mutabilis, but both of these species are found in coniferous woodland.
Lactarius quietus Taxonomy and Etymology
In 1821 the great Swedish mycologist Elias Magnus Fries gave it the binomial scientific name Agaricus quietus, but in 1838 Fries himself transferred this species to the genus Lactarius, thereby establishing its currently-accepted scientific name as Lactarius quietus.
Synonyms of Lactarius quietus include Agaricus quietus Fr., Galorrheus quietus (Fr.) P.Kumm., and Lactifluus quietus (Fr.) Kuntze.
The generic name Lactarius means producing milk (lactating) - a reference to the milky latex that is exuded from the gills of milkcap fungi when they are cut or torn. The specific epithet quietus comes from Latin and means quiet or calm, which is almost certainly a reference to the easily overlooked or quiet coloring of this mushroom.
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