Hygrocybe ceracea (Wulfen) P. Kumm. - Butter Waxcap

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

Hygrocybe ceracea - Butter Waxcap

Rarely more than 3cm in diameter and typically half that size, the Butter Waxcap gets its name not only from its colour but also from the buttery (waxy rather than glutinous) nature of its cap surface. Like so many of the small waxcaps, this species rarely fruits as a singleton, more often creating scattered groups over a large area.

The Butter Waxcap fruits from late summer to early winter, and is one of the few yellow waxcaps that are fairly easy to identify from characters that are readily visible in the field.

Distribution

Hygrocybe ceracea is common and widespread in Britain and Ireland, where it is most often seen in unimproved grassland and, much less often, in sand dunes and on woodland edges. It is a cold climate waxcap and most abundant in Scandinavia, becoming less common further south on mainland Europe. This species is also recorded in parts of North America.

Hygrocybe ceracea in acid grassland

Taxonomic history

Originally described in 1781 by Austrian mycologist Franz Xavier von Wulfen (1728 - 1805), who named it Agaricus ceraceus, the Butter Waxcap was relocated to its present genus in 1871 by the famous German mycologist Paul Kummer. (Prior to Kummer's work the vast majority of gilled fungi were simply recorded as Agaricus species.)

Synonyms of Hygrocybe ceracea include
Agaricus ceraceus Wulfen, Gymnopus ceraceus (Wulfen) Gray, Hygrophorus ceraceus (Wulfen) Fr. , Hygrocybe vitellinoides Bon, and Hygrocybe ceracea var. vitellinoides (Bon) Bon.

Etymology

The genus Hygrocybe is so named because fungi in this group are always very moist. Hygrocybe means 'watery head'.

This really is the archetypal waxcap, because its specific epithet ceracea comes from the Latin cera, meaning wax, and refers to the waxy surface of the cap of this neat little mushroom. The Butter Waxcap is not the type species of the Hygrocybe genus, however; that honour is reserved for the Blackening Waxcap Hygrocybe conica.

Note also that there another white-spored mushroom, Rhodocollybia butyracea formerly known as the Greasy Toughshank, is now more commonly referred to as the Butter Cap... it should not be confused with Butter Waxcap!

Identification guide

Cap and stem of Hygrocybe ceracea

Cap

0.5 to 3.5cm in diameter, the cap is hemispherical at first, becoming convex and eventually almost flat, sometimes with a slightly depressed centre. Initially the cap colour is bright yellow or orange-yellow, darker towards the centre, and the margin is translucently striate. As the fruitbody matures its cap margin fades slowly to white. Although they tend to be waxy and sticky in wet weather the caps are not slimy.

A hand lens reveals that the surface of the cap is covered in tiny nodules; this surface texture may be less evident or absent when the caps are fully expanded.

The cap flesh is orange.

Gills of Hygrocybe ceracea

Gills

Adnate or slightly decurrent, thin, fairly crowded (for a waxcap, that is), the gills are usualy a paler yellow than the cap and sometimes almost white. (Specimens with orange gills are also reported, but I have not seen this form.)

Stem

Yellow on the surface and within the stem flesh; sometimes tinged orange near to the base. Dry, smooth and silky or matt. Level, sometimes laterally compressed, usually hollow, with no stem ring; 2 to 4mm in diameter and 2 to 5cm tall.

Spores

Oblong to cylindrical, often constricted; smooth, 6.5-8 x 3-4 μm; inamyloid.

Spore print

White.

Basidia

Mainly four-spored.

Odour/taste

Not distinctive.

Habitat & Ecological role

In unimproved acid and neutral grassland, including upland meadows, parkland, old lawns and churchyards; occasionally on stable sand dunes and (more rarely) on woodland edges.

Season

August to November in Britain and Ireland.

Similar species

Gliophorus laetus the Heath Waxcap, has greyish decurrent gills.

Hygrocybe chlorophana is larger and has a more slimy cap in wet weather.

Hygrocybe reidii occasionally occurs in an all-yellow form; it is larger and its crushed gills smell like honey.

Gloioxanthomyces vitellina is more viscid; it has widely-spaced decurrent gills with hyaline (see-through) edges.

Culinary Notes

On a Europe-wide scale waxcap fungi are now quite rare, and so although in western Britain many of the acid-soil species are still plentiful most mycologists deplore the suggestion of these lovely fungi being gathered to eat. In any case the Butter Waxcaps are too insubstantial to be of any significant cullinary value.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Fungi of Northern Europe, Volume 1 - The Genus Hygrocybe, David Boertmann, 2010.

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.

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