Leratiomyces ceres (redlead roundhead)
Leratiomyces ceres (Photo: Geoffrey Kibby)
An introduced species, which is becoming widespread in much of Europe and North America, and is not of conservation concern. Uncommon in Australia but not of noted conservation concern.
Occurs primarily on woodchip mulch, continuing to fruit for several years as the wood chips decay. More information below.
About this species
Redlead roundhead is an alien species in Britain, and was first reported here in 1957, being recorded growing on sawdust in Somerset by Orton (1960). A subsequent collection from Surrey in November 1957 was described and illustrated by Reid. Since then it has spread widely and is now quite common in some areas, fruiting sometimes in abundance on woodchip mulch. It is occasionally also found away from woodchip in natural habitats.
It continues to be reported worldwide and is now known throughout much of Europe, North America, Australia and New Zealand. However, its mode of dispersal and colonisation are, as for other woodchip fungi, little understood.
At the Royal Horticultural Society’s garden at Wisley in Surrey, investigation of mulch and soil using DNA analysis showed somewhat inconsistent results but in general found that the fungus is present in soil, which may then provide a reservoir for colonisation of the mulch.
Until 2008 this species was known as Stropharia aurantiaca, and reference materials produced up until that point refer to it under that name.
Geography and distribution
Native to Australia, introduced in the northern hemisphere. Found in the UK, throughout much of continental Europe and now more widely in North America. Also known in New Zealand.
Occurs primarily on woodchip mulch, continuing to fruit for several years as the wood chips decay. It can occasionally found in natural habitat, on soil usually in wooded areas. In Australia, in its native habitat, it is found on rich soil amongst plant litter, or in grassy areas under trees.
Leratiomyces ceres is a distinctive and rather attractive fungus. It can be recognised by the orange cap, which is distinctly slimy especially in wet weather, and dark spores. It can be found growing in large clusters on woodchip mulch.
The fruitbodies appear in clusters and are usually tufted. The cap is orange or orange-red, 2 to 7 cm across, convex and flattened with age. The cap is sticky, smooth or sometimes slightly wrinkled at the centre. The edge of the cap is rolled under when young, and toothed with remnants of the veil. The gills are adnate (fused to the stalk), greyish-white at first, becoming blackish-purple as the spores mature. The edge of the gills is cottony-white when young. The stalk is white, 2 to 7 cm long, 5 to 10 mm thick, cylindric or slightly enlarged towards the base. The stalk has a ring zone arising from conspicuous white rhizomorphs (root-like groupings of fungal threads). The flesh is whitish and the spores are purple-brown.
Leratiomyces ceres was until recently known as Stropharia aurantiaca, a misidentification of a related but more slender orange species which is native to Europe. Leratiomyces ceres, first described from Melbourne as Agaricus ceres, is native to Australia, and recent study has confirmed that it does not belong in Stropharia but, together with some other related species, is appropriately referred to this typically tropical genus.
Threats and conservation
Uncommon in Australia but not considered of conservation concern.
Woodchip fungi and Kew
The suitability of woodchip mulch as a substratum for the colonisation of fungi has become increasingly evident in recent years, with an ever-growing number of species being recorded from it in many parts of the world.
The mulching of garden beds with woodchips has become a routine practice in Britain during the past twenty years or so, and provides a specialised, rather unique habitat which is not otherwise found in nature. Either as mulch or in composting piles, woodchip proves surprisingly ideal for many fungi from a wide range of groups, including common species found more usually in other habitats, and otherwise scarce species which can fruit in abundance.
In Britain, these are exemplified by the bird’s-nest fungi Cyathus olla and Crucibulum laeve , and by agarics such as Volvariella gloiocephala and Macrocystidia cucumis. Some woodchip fungi have even proved to be first recorded in Britain from this substratum, notably Melanoleuca verrucipes and Agrocybe putaminum, and yet others have proved to be undescribed and of unknown origin.
Perhaps the most recent example of the latter is Agrocybe rivulosa, first described from woodchips in the Netherlands as recently as 2003. This species was recorded in Britain from Staffordshire the following year, and has since spread rapidly in England with over 50 records to date.
Psilocybe cyanescens, first described as new to science from the Royal Botanic Gardens, Kew in 1911, was perhaps the first of the introduced woodchip fungi to be recorded in Britain. A compilation of fungi from woodchip which have been received at Kew now totals at least 250 species. Their origin, ecology and mode of dispersal are all little understood and in need of further study.
Redlead roundhead at Kew
Leratiomyces ceres was first recorded in the Gardens at Kew in 1957, very soon after its discovery in Somerset. It is now common at times and can be found on woodchip mulch spread on the beds around the Gardens, usually fruiting in the autumn months.
Preserved specimens of Leratiomyces ceres from throughout its range are maintained in the Kew Mycology Herbarium and, although not accessible to the general public, are available for study by research workers worldwide.
Bridge P, Prior C. (2007). Introduction or stimulation? The association of Stropharia aurantiaca with bark and wood-chip mulches. European J. Soil Biol. 43, 101–108.
Bridge, P.D., Spooner, B.M., Beever, R.E. & Park, D.-C. (2008). Taxonomy of the fungus commonly known as Stropharia aurantiaca, with new combinations in Leratiomyces. Mycotaxon 103: 109 – 121.
Encyclopaedia of Life
Fortey, R. (2004). Psilocybe aurantiaca and a case of mistaken identity. Field Mycology 5: 77 - 80.
Fungus Records Database of Britain and Ireland. Available online.
Orton PD. (1960). New Check List of British Agarics and Boleti. Part III. Notes on genera and species in the list. Trans. Brit. Mycol. Soc. 43: 159 - 439.
Pegler, D.N. & Legon, N.W. (1998). Stropharia aurantiaca. Profiles of Fungi 97. Mycologist 12: 180.
Reid, D.A. (1966). Coloured Icones of Rare and Interesting Fungi. 1: 29, pl. 8. Suppl. Nova Hedwigia XI.
Shaw, P.J.A., Butlin, J. & Kibby, G. (2004). Fungi of ornamental woodchips in Surrey. Mycologist 18: 12 - 15.
Shaw, P.J.A. & Kibby, G. (2001). Aliens in the flowerbeds. The fungal biodiversity of ornamental woodchips. Field Mycology 2: 6–11.
Kew Science Editor: Brian Spooner
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