Polyporus tuberaster is a small to medium sized (60-100mm at max), soft fleshed Polypore that can be found fruiting directly on soil or on wood.  As the epithet describes, this fungus has a sclerotia (tuber in the name) attached which is buried in the soil among roots and stones, this can weigh up to 15kg, but is usually far less.  If the fungus is found on wood it is still attached to this sclerotia via the wood.  P. tuberaster is most easily confused with Polyporus squamosus, an almost identical, bigger relative (up to 200-300mm), which is without the sclerotia, is far more common and fruits on a wider range of broadleaved deciduous trees, living or dead.  Both cause a white rot.

I was very lucky to spot this, as I was pointing out an area where I often record Agaricus osecanus, and there among the long grass, surrounding a Lime tree was this, Tricholoma argyraceum.  I was a bit surprised at the time of year but I needn’t have been as this species can occur during spring/late spring.  This is very closely related to Tricholoma scalpturatum which generally has much greyer and darker tones with more prominent scales, some authors consider them synonymous.  The very pale colouration and light brown scaling at the cap centre are a good characteristic of T. argyraceum.  A mealy smell has been noted from both species which varies in strength between collection, this had a feint smell.      Both species have the characteristic of yellowing, especially on the gills  The spores of both species are very narrow, only 2.5 to 4 microns.

May 30th 2013 – Agaricus osecanus is very closely related to the Horse Mushroom, Agaricus arvensis, yet it differs in a number of ways.  It has slightly smaller spores,  it tends to occur during late spring early summer, prefers to be close to trees and crucially it is whiter and remains so, with hardly any yellowing, unlike the Horse Mushroom which yellows more readily, both have the cog-wheel patterned partial veil and annulus (ring on stem).  The definition of A. osecanus  syn. A. nivescens is ‘Snowy Cap’.  Quite clearly shown in the picture below.  Note the pale gills of the more immature specimen, far left as you view.

May 21st – Kenwood – Agrocybe praecox – The Spring Fieldcap.  Now, I would go along with the spring bit but not sure about the fieldcap epithet as this species is most often found on wood chip mulch and other such rich based substrates but as it is shared with all other members of the genus, then best left alone.  Often among newly laid rose beds and such like.  This collection was fruiting directly on soil, most probably enriched by compost as it was inside a cold frame inside the gardeners bothy on the Kenwood Estate. It was also growing out alongside where some protective sheeting had been laid down.  It is a typical spring species but not entirely restricted to these early months, though this is most probably the best time to catch it.  Note the partial veil coming away from the edge the cap, revealing the pale gills beneath, the veil will form an annulus   (ring) on the stem, which helps to separate this species from the less common, non-native, look-alike,  Agrocybe putaminum, as this species has no partial veil to begin with.