Hygrocybe calciphila Arnolds - Limestone Waxcap

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

Distribution - Taxonomic History - Etymology - Identification - Culinary Notes - Reference Sources

Hygrocybe calciphila, Limestone Waxcap

There are several small red or orange waxcap species, and to separate them with any confidence it is necessary to study their microscopic features such as spore size and shape; however, most of them favour acid or neutral grasslands. The Limestone Waxcap grows on chalky grassland or in grassy habitats overlying limestone, and so knowing the soil pH in which waxcaps are growing can be a great help.

Hygrocybe calciphila, Limestone Waxcaps, southern England

Distribution

Restricted to alkaline unimproved mossy grassland, Hygrocybe calciphila is an infrequent to rare species in Britain and Ireland, and it occurs also in parts of mainland Europe. This tiny waxcap is also recorded in the USA, where it grows in unimproved base-rich grassland and occasionally in open woodlands.

Taxonomic history

The Limestone Waxcap was first described scientifically in Persoonia in 1985 by the distinguished Dutch mycologist Eef Arnolds (b. 1948), who gave it the name Hygrocybe calciphila. This remains its accepted scientific name.

Synonyms for Hygrocybe calciphila include Pseudohygrocybe calciphila (Arnolds) Kovalenko and Hygrocybe calcarum Gröger.

Etymology

The genus Hygrocybe is so named because fungi in this group are always very moist. Hygrocybe means 'watery head'. The specific epithet calciphila means calcium loving - a reference to the chalk-based and limestone-based grassland habitats favoured by this waxcap species.

Identification guide

Cap of Hygrocybe calciphila

Cap

3 to 25 mm across; initially convex, becoming flat-topped and often eventually developing a slight depression; shades of red to reddish-orange, often with a narrow yellowish margin; dry and finely scaly.

Pileipellis

A trichoderm.

Gills of Hygrocybe calciphila

Gills

Broadly adnate; yellowish or pale orange, paler at the edges.

Basidia

Mainly four-spored.

Gill trama

Subregular with cylindrical or slightly inflated elements typically to 140 µm long.

Stem of Hygrocybe calciphila

Stem

2 to 4 cm long and 1.3 to 3 mm diameter, sometimes compressed with a longitudinal groove;; dry and matt or with a fine silky sheen; orange or golden yellow; no stem ring.

Spore of Hygrocybe calciphila

Spores

Broadly elipsoidal; 7.5-9 x 5-6 µm; inamyloid.

Spore print

White.

Odour/taste

Not distinctive.

Habitat & Ecological role

Closely cropped or mown grassland where artificial fertilisers are not spread. (In the USA in particular this species is sometimes recorded from open woodland habitats.)

Waxcaps have long been considered to be saprobic on the dead roots of grasses and other grassland plants, but it is now considered likely that there is some kind of mutual relationship between waxcaps and mosses.

Season

September to November in Britain and Ireland.

Similar species

Hygrocybe coccinea has a larger orange-red cap.

Hygrocybe miniata, a more gregarious waxcap which favours acidic to neutral grassland habitats, also has a scurfy reddish cap; most of its spores are mitriform rather than ellipsoidal.

Hygrocybe calciphila - Limestone Waxcap, closeup picture of cap, stem and gills

Culinary Notes

Although reported in some field guides to be edible, these tiny waxcaps are so insubstantial that they are surely not worth collecting for the pot. A collector would probably burn up far more calorioes in gathering a dish of Limestone Waxcaps than the meal would contain... so maybe these are 'slimming mushrooms'!

Reference Sources

Fascinated by Fungi, 2nd Edition, Pat O'Reilly 2016, reprinted by Coch-y-bonddu Books in 2022.

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.

Acknowledgements

This page includes pictures kindly contributed by Simon Harding.

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