Lactarius torminosus

German naturalist Jacob Christian Schäffer was the first to describe the species, placing it in the genus Agaricus in 1774. A 2004 phylogenetic analysis of European Lactarius species concluded that L. torminosus falls into a group that includes L. torminosulus, and that these two species are closely related to a group that includes L. tesquorum, L. scoticus, and L. pubescens. A multi-gene molecular analysis published in 2008 demonstrated that species then distributed in the genera Lactarius and Russula actually consisted of four distinct lineages. The subsequent reorganization of Russulaceae species—a taxonomic change needed to make Russula and Lactarius monophyletic—required that a new type species be defined for Lactarius, since the previous type, L. piperatus, belonged to the clade that will be transferred to genus Lactifluus. A proposal to conserve Lactarius with L. torminosus as the type was accepted by the Nomenclatural Committee for Fungi and passed at the 2011 International Botanical Congress. The change minimizes "taxonomic disruption", allowing most of the common and well-known Lactarius species to retain their names. Etymology The specific epithet torminosus means "tormenting" or "causing colic", in reference to the gastrointestinal distress associated with consuming the raw mushroom. Early English vernacular names were Gray's "bellyach milk-stool" (1821), and James Edward Smith's "bearded pepper agaric" (1824). More recent common names include "shaggy milkcap", "powderpuff milkcap", "pink-fringed milkcap", "bearded milkcap", and the British Mycological Society-recommended "woolly milkcap". ==Description==

The cap is initially convex, but as it matures the center forms a depression and the outer edges rise until it assumes the shape of a shallow funnel; its final width is typically between . The fruit body formation of L. torminosus is pileostipitocarpic. In this type of development, the hymenium forms early on the underside of the cap and upper stem of the mushroom primordium. As the cap enlarges, the margin, made of flaring filamentous hyphae that grow outward and downward, tends to curve inward, eventually forming a flap of tissue roughly parallel to the stem surface. As further development takes place, these hyphae make contact with and adhere to the hymenial surface of the stem, covering basidia and macrocystidia (very long cystidia) already present. The junction between the two tissues produces a cavity that provides some temporary protection to the basidia, although they are already fertile when the cap margin starts to grow. The holotype specimen of L. torminosus var. nordmanensis was collected by Smith in 1956 near Nordman, Idaho. L. subtorminosus was named for its similarity to L. torminosus. It can be distinguished by its mild-tasting latex and smaller, roughly spherical spores measuring 5.5–7 by 5.5–6.5 μm. In North America, L. psammicola grows with eastern hardwoods and L. subvillosus appears in tanoak-madrone woodland. == Distribution and habitat ==

Lactarius torminosus is found in northern temperate and boreal climates, penetrating sometimes into subarctic regions. It has been recorded from North Africa, northern Asia, Europe, and is common in North America, where it sometimes grows with aspen (Populus species). The North American distribution extends north into the Yukon and Alaska and south to Mexico. ==Ecology==

Lactarius torminosus is a mycorrhizal species, and as such plays an important role in facilitating nutrient and water uptake by trees. It grows in association with birch (Betula) and hemlock (Tsuga) in mixed forests. It is also known to grow in urban settings when birch trees are nearby. A field study in Scotland concluded that the species is more likely to be present in older than in younger birch woodlands. Fruit bodies grow on the ground, scattered or grouped together. They are a component of the diet of the red squirrel, and serve as breeding sites for some fungus-feeding flies in the Drosophilidae and Mycetophilidae families. Lactarius torminosus mushrooms may be parasitized by the mold Hypomyces lithuanicus, which produces a cream-ochre to cinnamon-colored granular or velvety growth of mycelium on the surfaces of the gills and causes them to be deformed. ==Toxicity==

The intensely peppery taste of the raw mushroom can blister the tongue if sampled in excess. Some authors have reported the species as outright poisonous, or causing "mild to fatal gastroenteritis". In a 1930 publication, Hans Steidle reported that although the mushroom was not toxic to "unicellular and cold-blooded organisms" when ingested, the liquid extract and the pressed juice of the fruit bodies, when injected under the skin of a frog, resulted in disturbed breathing, paralysis, and eventually death. Symptoms that are typically experienced after consuming raw mushrooms include nausea, vomiting, and severe diarrhea starting about one hour after ingestion. This combination can lead to dehydration, muscle spasms, and circulatory collapse. The gastroenteritis will usually resolve without treatment in a couple of days. == Uses ==

Despite the reports of toxicity, L. torminosus mushrooms are prepared in Finland, Russia, and other northern and eastern European countries by parboiling, soaking in brine for several days, or pickling, after which they are valued for their peppery taste. Mushrooms are harvested for commercial sale in Finland. The nutrient composition of Finnish specimens has been analyzed and found to contain the following components (as a percentage of dry weight): protein, 17.20%; phosphorus, 0.46%; calcium, 0.12%; magnesium, 0.09%; potassium, 2.97%; sodium 0.01%. ==Chemistry==

The compound thought to be responsible for the toxicity of raw L. torminosus is the pungent-tasting velleral present at a concentration of 0.16 mg/g mushroom. Velleral is a breakdown product of stearyl-velutinal. Broken lactifers—specialized hyphal cells that produce the mushroom's latex—leak the precursor chemicals whose breakdown products act as the defensive agents toxic to humans, effectively deterring certain vertebrates that might consume the mushroom. The lactarane-type lactone 15-hydroxyblennin A is one of several sesquiterpenes produced by the species. Other lactaranes are found in various Lactarius species, such as blennin A in L. deliciosus and L. blennius, and lactarorufin N in Lactarius rufus. Fungal sesquiterpenes are commonly produced as toxins to defend against predation, and as a result some have chemical properties that may have applications in medicinal chemistry. Fruit bodies of L. torminosus contain a number of sterols, of which ergosterol (a component of fungal cell walls) is the most predominant at 60.5% of all sterols, followed by its derivatives and ergosta-5/7-dien-3-ol (17.0%), ergost-7-en-3-ol (13.7%) and ergosta-7-22-dien-3-ol (8.3%). Researchers have identified 28 volatile compounds that contribute to the odor of the mushroom. Many of these are alcohols and carbonyl compounds with eight carbon atoms; the predominant volatile compound (about 90%) is 1-octen-3-one, an odorant common in mushrooms. ==See also==