Leucoagaricus crystallifer Vellinga

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Agaricaceae

Leucoagaricus crystallifer

Looking rather like one of the many pale Lepiota and Leucocoprinus dapperlings, Leucoagaricus crystallifer is a very rare find in Britain. The specimens shown on this page were found in 2013 by Sue O'Reilly on the edge of deciduous woodland in Cambridgeshire. Three other records of this beautiful mushroom in the Fungal Records Database for Britain and Ireland (FRDBI) were all made between 1999 and 2005 and are from Somerset (two sightings) in southwest England and Brecon (one sighting) in Wales.

Leucoagaricus crystallifer, showing the clavate stem base

Distribution

There are insufficient records to describe meaningfully the distribution of this species in Britain and Ireland, but it is quite possible that its appearance in recent years may be due to climate change. This dapperling mushroom occurs in many parts of mainland Europe, from Scandinavia to the Mediterranean, but it seems to be an uncommon to rare find throughout its range.

Taxonomic history

This lovely dapperling mushroom was described in 2000 by American mycologist Else C Velinga, who gave it the scientific name Leucoagaricus crystallifer by which it is generally known today.

Sericeomyces crystallifer (Vellinga) Bon is a synonym of Leucoagaricus crystallifer. Because of its rarity, this mushroom does not have a generally-accepted English common name.

If I was asked to think up a common name for Leucoagaricus crystallifer, I would have to suggest 'Crystal Tipps' - after the BBC TV cartoon characters Crystal Tipps and Alistair created by Hilary Hayton and Graham McCallum in the early 1970s - but also of course in reference to the crystals which cling to the tips of this mushroom's cheilocystidia.

Etymology

Leucoagaricus is derived from the Greek Leucos meaning white and Agaricus, the genus name of the 'true mushrooms' as many people call the Field Mushroom, Horse Mushroom and their close relatives all of which have pink gills that darken when the brown or purple-brown spores mature. So Leucoagaricus suggests a group of white mushrooms that are in many respects similar to Agaricus species.

The specific epithet crystallifer means 'bearing crystals' and is a reference to the crystals of calcium oxalate which largely cover the tips of its fusiform cheilocystidia.

Identification guide

Caps of Leucoagaricus crystallifer

Cap

Initially ovoid and then convex, expanding to become almost flat with a small umbo; often smooth and silky but occasionally with tiny flakes or scales; white, gradually becoming flushed pale cream-ochre or flesh-coloured.

Cap diameter at maturity ranges from 2 to 5cm.

Gills of Leucoagaricus crystallifer

Gills

The free, crowded gills are pure white at first, eventually becoming pale flesh-pink.

Stem

4 to 7cm long and 4 to 10mm in diameter, white; smooth with a thin persistent ring; cylindrical with a clavate base.

Spores of Leucoagaricus crystallifer

Spores

Ellipsoidal to amygdaloid, smooth, 8.3-10 x 4-5µm; dextrinoid.

Spore print

White.

Odour/taste

Not significant.

Habitat & Ecological role

Saprobic, found either singly or in small groups in or at the edge of deciduous woodland.

Season

Fruiting season of this mushroom in Britain is unclear due to insufficient data; the few specimens found to date have appeared in autumn.

Similar species

Most likely to be confused with small dapperlings of the Lepiota or Leucocoprinus genera, many of which are entirely or mainly white when young and fresh.

Culinary notes

This species is so rare that not only is there no reliable information about its edibility but also these mushrooms should not be gathered except where necessary for serious scientific study.

Reference Sources

Leucoagaricus crystallifer Vellinga, Persoonia 17(3): 475 (2000)

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.

Acknowledgement

We are grateful to Geoffrey Kibby, who kindly checked and confirmed the identity of the specimens shown on this page.

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