Common Name: Russula – Due to the lack of distinction among the many species of Russula mushrooms, they are commonly known by the genus name.
Scientific Name: Russula spp – The generic name is derived from the Latin word russus, meaning red; many of the mushrooms in the Russula genus have a red pileus (cap). The designation spp is an abbreviated form for species (sp) plural and indicates that it refers to a number of species.
Potpourri: Mushroom species of the genus Russula are probably the most maligned and mistreated of all of the members of the Fungi Kingdom. If the Morel (Morchella esculenta) is the queen of mushrooms and the Cep (Boletus edulis) is the king, then surely the Russula is the knave. Their fragility and dubious culinary merit subject the Russula to sneering contempt even by mycophilic people. Russulas, which are otherwise commendable and attractive mushrooms, are among the most ubiquitous in sylvan habitats, with over 700 species identified worldwide. Many have a red cap, though there are a wide variety of colors that range from gold to green. Other than the cap color, almost all Russulas have the same basic features: generally stolid and squatty; a cap that is flat to slightly depressed at maturity that is wider in diameter than the height; and a thickset stem that lacks the tell-tale ring of a partial veil, is smooth with no striations, and is for the most part pure white.
The most notable and unique characteristic of the Russula mushroom is the brittleness of the flesh – a factor so important that Russulas are called “brittlegills” in The Peterson Field Guide to Mushrooms. This makes them very easy to identify in the field – one can readily break off a section of the pileus (cap) with minimal shear force. This can be clearly demonstrated by hurling one against the ground – it will literally shatter into hundreds of fragments; an alternative is the Russula dropkick. In either case, an appropriate imprecation such as “JADRR” (Just another damned red Russula) can be used to emphasize the calumny. The reason that the flesh of the Russula is so brittle compared to the greater pliability of other mushrooms is that the cellular structure of the Russula and the closely related mushrooms of the genus Lactarius is distinct among the fungi. While most mushrooms have an elongated, fibrous cell structure that will bend but not break, the Russulas have globular cells called sphaerocytes that are intermingled with the elongate cells. It is these roundish cells that allow cracks to rapidly propagate through the mushroom so that the flesh will undergo brittle fracture, rapid cracking with little or no deformation in a manner reminiscent of chalk. It is hypothesized that the formation of sphaerocytes occurred due to evolutionary pressures to more rapidly expand the epigeal (above ground) fruiting body to expedite spore dissemination. This is based on the observation that the Russulas that are indigenous to tropical habitats are comprised almost entirely of sphaerocytes while those in temperate regions have a mixture of the fibrous and sphaerocytic cells.
Distinguishing the myriad species of Russula is a challenge of gargantuan and perhaps Sisyphean proportions. Although many Russulas are red, they can vary greatly in color. As an example, one of the more common species is ”extremely variable” in color according to Gary Lincoff in the renowned National Audubon Society Field Guide to North American Mushrooms, ranging from greenish to pinkish with many intermediate hues. It is not surprisingly named R. variata. Since color is not a good means to distinguish one Russula from another, a number of other distinctions have been proffered as a means of identification. In addition to the color, shape and ornamentation of the spores, the most common and reliable identification key for mushrooms and the basis for many taxonomies, Russulas also can purportedly be speciated according to the bitterness of the taste, the pungency of the smell, changes to the color of the flesh both with and without the use of chemical reagents, and the degree to which the tough, colored skin of the cap can be pulled away from the margin before it snaps off. According to David Aurora in Mushrooms Demystified, “no two look quite alike” because they are “unusually sensitive to environmentally and genetic caprice.”
The variability of mushrooms according to their specific habitat that is manifest in the Russulas is a reflection of the fact that they are heterotrophic and must therefore seek nourishment from external sources (only plants are autotrophic) and that they are by their very nature part of the intertwined anastomosis of the forest soil. All Russulas are mycorrhizal which means that they are obligate in their association with the roots of the host plants, predominantly trees; mycorrhizal is from the Greek mykes meaning fungus and rhiza, meaning root literally ‘fungus root.” This is a mutualistic relationship as both the tree and the fungus gain from the association. The tree gains what is essentially an extended root system in the spreading hyphae (root-like fungal tendrils) of the fungal mycelium (the hypogeal “body” of the fungus) that provides not only an increased water volume for absorption, but also the essential minerals from the soil. But what is probably the most important factor for the tree is that the mycorrhizal fungus stores these essential mineral nutrients, notably ammonium (for the nitrogen) and phosphate (for the phosphorus), making them available for use during periods of resource paucity, like a drought, or to support a period of rapid tree growth. It is hypothesized that the mycorrhizal relationship is the primary reason why trees predominate in cool temperate and cold boreal climates. So what does the Russula get out of the association? It gets sugars that are the photosynthates produced by the tree; it is estimated that as much a 10 percent of the trees entire output is provided to the mycorrhizal fungus through the root – hypha interface. Russulas in general are mycorrhizal with many trees, though there is a particularly strong association with oak, beech and birch.
The edibility of Russulas is subject to a wide range of written opinion and conjecture that ranges from the panegyric to the pasquinade. This is likely the result of the great degree of variability of the Russulas in appearance that is manifest in variability of taste. The best way to determine whether a Russula is edible is to take a small bite and ascertain whether the taste is mild or acerbic. There is no known species of Russula that is deadly and the Russulas that have a mild taste are edible. If it is acerbic, it is a good indication that it will result in intestinal distress. One of the more common Russulas that fall into this category is the Russula emetica, the species name derived from the Greek emetikos, to vomit, reported to be a strong purgative. According to Charles McIlvaine in One Thousand American Fungi, “when they present no objectionable appearance or taste, their caps make the most palatable dishes when stewed, baked, roasted or scalloped.” On the other hand the Russians, who are perhaps the most mycophilic peoples of all of Europe, call the Russula the СЫРОЕЖКА, pronounced “Sarah-yeshka” which literally means “eat raw” with the assumed implication that it is so mediocre that it is not even worth bothering to cook. However, it is more likely that the meaning is related to the common practice in Russia of collecting and cleaning the abundant Russulas in the summer and fall and placing them in a barrel in layers alternated with salt strata as a means of preservation and flavor enhancement. These were then “eaten raw” during the long, cold winters, the saltiness a good adjunct to vodka.