Oyster cap fungus, Pleurotus ostreatus

Fruiting bodies of the Oyster cap fungus, Pleurotus ostreatus on a dead horse chesnut tree, Aesculus hippocastanum, in the UK in January. The picture shows mature clusters of the fungus ( pale orange/brown) emerging from the bark of the tree, seen from below. The widely spaced gills descend to cover the short stalk (stipe), which is branched at the point of attachment to the tree, not visible here. The fungus is living as a saprophyte on the dead wood.Dead hardwood is nutritionally poor in nitrogen.Pleurotus species are remarkable for their ability to capture and digest nematodes to overcome this. The fungus produces short hour-glass shaped extensions from its hyphae (that permeate the wood mass). These exude a glue that entraps any passing nematode, and a toxin that immobilises it. Hyphae then grow into the nematode and digest it. P. ostreatus is edible, but of a rather mild flavour.