What You Should Know
Psathyrella piluliformis is an edible (but low quality) species of agaric fungus in the family Psathyrellaceae. It produces fruit bodies (mushrooms) with broadly convex caps measuring 2–5 cm (0.8–2.0 inches) in diameter. The caps are chestnut to reddish-brown, the color fading in age and with dry weather. The closely spaced Gills have an adnate attachment to the stipe. They are initially tan until the spores mature when the gills turn dark brown.
Fragments of the partial veil may remain on the cap margin and as a wispy band of hairs on the stipe. Fruiting occurs in clusters at the base of hardwood stumps.
This mushroom looks like a whole bunch of other Psathyrella species but can be tentatively identified based on its tendency to grow in clusters on the wood of hardwoods and the band of white veil tissue running along the margins of young caps.
Other names: Common Stump Brittlestem, Clustered Psathyrella.
Psathyrella piluliformis Mushroom Identification
Saprobic; growing in small to large clusters on wood or deadwood of hardwoods or woody debris; sometimes appearing terrestrial but then probably arising from buried wood; spring through fall, or overwinter in warm climates; widely distributed in North America; also widely distributed in Europe.
3–7 cm; convex, becoming broadly convex; a little sticky when fresh; bald; brown to reddish-brown or honey brown when fresh, but changing color markedly as it dries out, to dull tan; when young with a belt of white veil tissue along the margin.
Broadly attached to the stem; close; short-gills frequent; whitish to pale brownish first, becoming dull grayish brown.
6–9 cm long; 4–9 mm thick; equal; fragile; bald or very finely silky; whitish, discoloring brownish were handled; without a ring.
Thin; fragile; watery brownish.
Odor and Taste
Spores 5–6 x 2.5–3.5 µm; ellipsoid; with a very tiny pore; smooth; brownish in KOH. Lamellar trama parallel. Pleurocystidia 30–50 x 10–15 µm; utriform; smooth; thin-walled; hyaline in KOH. Cheilocystidia 35–50 x 7.5–10 µm; widely cylindric to subutriform; smooth; thin-walled; hyaline in KOH. Pileipellis hymeniform/cellular; terminal elements 15–30 µm across, subglobose, smooth, hyaline to orangish brown in KOH.
Kuehneromyces mutabilis, the Clustered Woodtuft or Brown Stew Fungus, also grows in tufts on stumps; it has a ring on the stem, and the stem is brown and, rather than being smooth, is covered in scales at the base.
Psathyrella piluliformis Taxonomy and Etymology
The basionym of this species dates from 11783, when French mycologist Jean Baptiste Francois (Pierre) Bulliard described the Clustered Brittlestem, giving it the binomial scientific name Agaricus piluliformis. It was not until 1969 that this mushroom was given its currently-accepted scientific name; that was when British mycologist Peter Darbishire Orton (1916 - 2005) transferred this species to the genus Psathyrella, whereupon its name became Psathyrella piluliformis.
Synonyms of Psathyrella piluliformis include Agaricus piluliformis Bull., Agaricus hydrophilus Bull., Hypholoma hydrophila (Bull.) Quél., Hypholoma piluliforme (Bull.) Gillet, Hypholoma subpapillatum P. Karst., Drosophila hydrophila (Bull.) Quél., Drosophila piluliformis (Bull.) Quél., Psathyrella hydrophila (Bull.) Maire, and Psathyrella subpapillata (P. Karst.) Romagn.
Many recent field guides have this species listed under Psathyrella hydrophila. The specific epithet hydrophila means water-loving, and this wood-rotting mushroom certainly does seem to prefer damp places.
These woodland species are distinguished microscopically from several similar convex-capped mushrooms by their small spores; however, if you do not have a microscope then try to find some immature caps and you will see that the gills are enclosed beneath a partial veil that is fibrillose-cortinate. As the cap of the mushroom expands fibers of the partial veil remain attached to the rim of the cap and form a continuous dark band.
Psathyrella, the genus name is the diminutive form of Psathyra, which comes from the Greek word psathuros meaning straw-like, fragile or friable; it is a reference to the crumbly nature of the caps, gills and stems of mushrooms in this genus. The specific epithet piluliformis may come from the Latin noun Pila, meaning a ball (or a bullet), or perhaps Pilum meaning a javelin; with the suffix -formis meaning in the form (or shape) of.
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