A slime mould - Craterium minutum

Image: © Lairich Rig Taken: 17 Jan 2019

The setting is the area shown on the left in Image; specifically, the picture shows an oak leaf among the leaf litter a few metres away from the lip of the old quarry. Leaf litter is an important habitat for slime moulds. This is not a microphotography site, and the picture shows only the kind of details that might be discerned by someone with keen eyesight; a web search for the species name will find many much closer views. The individual sporangia (spore-producing structures) resemble tiny goblets, each about a millimetre high, with a white lid; when this lid is gone, a fine network called the capillitium is exposed to view; the spores are borne on that structure. As a rule, a microscopic examination is needed in order to identify slime moulds to species. However, as Bruce Ing's identification handbook mentions in connection with Craterium minutum, "the neat orange-brown goblets with a white lid are easily separated from all other species". The species is described as common, although this does not necessarily equate to being easy to find; slime moulds on wood are often more visible, but this species is associated instead with leaf litter (or plant stems), and is not so readily apparent. A few days earlier, I had noticed a different species in the same area (it was superficially similar to Image); on that occasion, I had spotted a single example of Craterium minutum from a few feet away, but did not photograph it. On a subsequent visit, some time searching among the oak leaf litter eventually turned up the (slightly better) example shown here. [On the scientific name: "minutum" means just what it seems to, while the genus name "Craterium" alludes to the form; the Greek κρατήριον is a diminutive form of κρατήρ (cratēr, "mixing vessel").]

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