''Psathyrella'' is a large

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of about 400 species, and is similar to the genera ''

Coprinellus ''Coprinellus'' is a genus of mushroom-forming fungi in the family Psathyrellaceae. The genus was circumscribed by the Finnish mycologist Petter Adolf Karsten in 1879. Most ''Coprinellus'' species were transferred from the once large genus ...

'', '' Coprinopsis'', '' Coprinus'' and '' Panaeolus'', usually with a thin cap and white or yellowish white hollow

stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushr ...

. The caps do not self digest as do those of ''Coprinellus'' and ''Coprinopsis''. Some also have brown

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

s rather than black. These fungi are often drab-colored, difficult to identify, and all members are considered inedible or worthless (for eating) and so they are often overlooked. However they are quite common and can occur at times when there are few other mushrooms to be seen. The first report of a gilled mushroom fruiting underwater is '' Psathyrella aquatica''. The genus name ''Psathyrella'' is a diminutive form of ''Psathyra'', derived from the Greek word ψαθυρος, ''psathuros'' 'friable'. The type species of ''Psathyrella'' is ''Psathyrella gracilis'', which is now known as ''Psathyrella corrugis''.

Characteristics

In order to identify the species it may be necessary to take into account the presence and nature of any

veil A veil is an article of clothing or hanging cloth that is intended to cover some part of the head or face, or an object of some significance. Veiling has a long history in European, Asian, and African societies. The practice has been prominent ...

remnants on cap (which may only be visible on very young fruiting bodies), the colour of young fruiting bodies, which is often more vivid than with older ones, whether the cap is

hygrophanous The adjective hygrophanous refers to the color change of mushroom tissue (especially the pileus surface) as it loses or absorbs water, which causes the pileipellis to become more transparent when wet and opaque when dry. When identifying hygrop ...

(it can well be a translucent brown or

ochre Ochre ( ; , ), or ocher in American English, is a natural clay earth pigment, a mixture of ferric oxide and varying amounts of clay and sand. It ranges in colour from yellow to deep orange or brown. It is also the name of the colours produce ...

colour in a humid state but a pure opaque white on drying out), and the spore size and the presence and nature of cheilocystidia, pleurocystidia and caulocystidia, distinctive sterile cells on the gill face, gill edge and stipe respectively. All Psathyrella species are unusually fragile, and both the cap and stem break with very little effort. Unlike most agarics, the caps of ''Psathyrella species'' easily break into triangular shaped pieces.

Selected species

''For complete list see'' List of ''Psathyrella'' species * '' Psathyrella ammophila'' (dune brittlestem) * '' Psathyrella aquatica'' * '' Psathyrella bipellis'' * '' Psathyrella candolleana'' (pale brittlestem) * '' Psathyrella corrugis'' (red edge brittlestem) (type sp., older synonym of ''Psathyrella gracilis'') * '' Psathyrella piluliformis'' / ''Psathyrella hydrophila'' (common stump brittlestem)

References

*Marcel Bon : ''The Mushrooms and Toadstools of Britain and North-Western Europe'' (Hodder & Stoughton, 1987).

External links

''The North American species of'' Psathyrella
by Alexander H. Smith, 1972. (Full text of monograph.) {{Taxonbar, from=Q2705558 Psathyrellaceae Inedible fungi Agaricales genera Taxa named by Elias Magnus Fries