Paralepista flaccida

Paralepista flaccida is a species of mushroom found across the Northern Hemisphere. It is known to form fairy rings.

Taxonomy

The naming history of this mushroom is complicated by the fact that for a long time it was regarded as two different species, "flaccida" and "inversa". These forms can still be differentiated as varieties within P. flaccida if desired. The earliest description was by Giovanni Antonio Scopoli in 1772 as Agaricus inversus in his book, then in 1799 James Sowerby created a description under the name Agaricus flaccidus in his major work "Coloured Figures of English Fungi or Mushrooms". In later years there were defined the combinations Clitocybe flaccida, Clitocybe inversa, and Lepista flaccida and Lepista inversa. There followed long-standing confusion over whether Clitocybe or Lepista was the appropriate genus.
Using molecular analysis, in 2012 Alfredo Vizzini published a paper showing that these mushrooms together with Lepista gilva form a clade which is separate from other Lepista species and also from Clitocybe species. Jörg H. Raithelhuber had already proposed the name Paralepista as a genus for those mushrooms in 1981, this had become accepted as a subgenus only, and Vizzini accordingly adopted the same name at the genus level. The new genus is recognized by Species Fungorum, and the Global Biodiversity Information Facility, but not necessarily in derivative databases such as the .
Older mushroom references generally listed the flaccida and inversa forms as separate species, but modern authorities merge them into one.
In English P. flaccida is sometimes called the tawny funnel cap.

Description

The convex cap grows up to wide. It is depressed in the centre or funnel-shaped when old and has a variable brownish colour which may be ochraceous, orange or reddish. In the flaccida form the upper surface is matt and silky and the mushroom as a whole is flaccid. In the inversa form the surface is shiny and the mushroom is rigid.
The gills are decurrent and closely packed, with a lighter hue than the cap. The yellowish stem is up to long and 1 cm thick. The flesh is whitish with a peppery smell. The spore print is white to cream.

Microscopic characteristics

The spores are almost spherical with small spines or warts, about 4.5 μm in diameter. There are no distinctive cystidia. There is no microscopic difference between the flaccida and inversa forms.

Similar species

The inversa form is sometimes regarded as a separate species, in which case it is distinguished because it grows under conifers rather than broad-leaved trees, has a shinier cap surface, and is more rigid.
Both forms are closely allied to the edible Paralepista gilva, which can be identified by its yellower cap and stem, and the presence of dark spots on the cap surface. Infundibulicybe gibba has thinner flesh, less crowded gills, and smooth teardrop-shaped spores.
More worrying for consumers of this species is the resemblance to the poisonous Paralepistopsis amoenolens, which seems to be limited in distribution to North Africa, southern France and southern Italy. P. amoenolens has a strong characteristic smell, a beige colour, and a less depressed cap; also the spores are smooth.

Habitat and distribution

This fungus is a saprobe growing on humus-rich soil, compost or conifer needles from summer to autumn. The flaccida form grows in deciduous woods and the inversa form under conifers. Often numerous mushrooms "fruit" together and it may form fairy rings.
It is most frequent in Europe where it is common. It also occurs in the U.S. and there have been reports of it from Mexico, and Australia.

Uses

According to Marcel Bon this is a good edible mushroom, but other commentators are less enthusiastic, regarding it as poor. In relevant regions care should be taken to avoid confusion with Paralepistopsis amoenolens. At least one source says that it is not recommended for consumption.
This thus mushroom has multiple chemical defenses. It contains a chlorinated lactone, 5--3-methyl-2-furanone that is a slug antifeedant. In addition, it has a new insecticidal nitro nucleoside, clitocine.
An article in Nature Communications reports that an extract of this mushroom, with active constituent 2,6-diaminopurine, can correct RNA nonsense mutations and so may be a candidate to help treatment of certain genetic diseases.