Leratiomyces ceres (redlead roundhead)

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.

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.