Parasola plicatilis (Curtis) Redhead, Vilgalys & Hopple - Pleated Inkcap

Taxonomy

Phylum: Basidiomycota

Class: Agaricomycetes

Order: Agaricales

Commonly referred to as the Pleated Inkcap, and sometimes as the Little Japanese Umbrella, Parasola (formerly Coprinus) plicatilis is a very delicate member of the inkcap group of fungi. It occurs in short grass.

This is one of the many short-lived grassland fungi that appear overnight following rain; the fruitbodies develop, expand, shed their spores and decay within 24 hours and by the next morning there is usually little or no evidence of them ever having existed.

If you have a lawn and you don't smother it in artificial weedkillers and fertilisers, this is one of the little mushrooms that you are likely to see. You need to get up early in the morning to see Parasola plicatilis at its very best, because by afternoon the stem usually begins to collapse under the weight of the darkening cap.

Until 2001 this little inkcap was classified as Coprinus plicatilis, a name given to it by American botanist Moses Ashley Curtis (1808 - 1872). In 2001, based on DNA sequencing, Redhead, Vilgalys & Hopple redistributed the species formerly collected in the Coprinus genus, and the Pleated Parasol was moved to the genus Parasola along with a great many superficially similar little mushrooms. (A microscope is essential to separate the various Parasola species with certainty, and even then it is no task for a beginner.)

Identification guide

	Cap The cap of Parasola plicatilis has a diameter of 1 to 2cm, is heavily ribbed, and initially egg-shaped, then convex and finally flat. A distinctive tawny central 'eye' contrasts with the rest of the pale grey cap.
	Gills The white gills turn grey and then black; they radiate from a collar around the top of the stem (unlike those of Parasola auricoma, which are adnate or adnexed to the stem) and are thin and quite well spaced. Unlike many of the inkcaps, this delicate little fungus has a cap that flattens and then shrivels rather than its gills deliquescing (turning to a black inky liquid).
	Stem Up to 6cm long, but only 4 or 5mm in diameter, with a slightly swollen base, and very fragile, the stem of Parasola plicatilis is faintly fibrillose; its colour is white or dingy cream becoming slightly brownish at the base.
	Spores Almond shaped: irregularly ellipsoidal in minor axis cross section and ellipsoidal in major axis cross section, 10-13 x 7-10.5 x 6.5-8μm with an eccentric germ pore - visible in many but not all of the spores pictured on the left. Spore print Black in mass.
Odour/taste	Not distinctive.
Habitat	Parasola plicatilis is a saprobic mushroom; it appears in short grass on lawns and sometimes in parks and meadows, usually in small groups.
Season	May to November.
Occurrence	Widespread and frequent throughout Britain and Ireland as well as in most parts of mainland Europe.
Similar species	Parasola auricoma is slightly larger and darker in cap colour; it has minute hairs among its cap cells, and it grows in woodland habitats and on woodchip mulch. Parasola kuehnerii is more orange-brown but is otherwise very similar in macroscopic appearance to Parasola plicatilis; this species is found mainly on woodland edges.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2011

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.