Cylindrobasidium laeve

Names

English Name: Tear Dropper

(other scientific names Cylindrobasidium evolvens, Corticium laeve, Butlerelfia eustacei, Thelephora evolvens, Corticium evolvens, Corticium laeve f. cucullata and Cladoderris minima)

With the British Mycological Society running a Corticioid Workshop at the end of February followed by a Corticioid weekend at Mar Lodge in March, I thought that I would take the opportunity to highlight this group of fungi again (see December's Fungus of the Month Cytidia salicina).

The name ‘Corticioid’ is taken from the Latin ‘cortici’ which has a range of meanings including ‘bark’, ‘rind’ or ‘shell’. In modern fungal use it refers to an artificial group of genera (in other words they are not necessarily closely related), they just all have this similar, rather simple growth form – often appearing not unlike bark or rind covering a piece of dead wood. They are also referred to as the ‘crust fungi’ or resupinates. The fertile surface can be smooth (actually, if you look with a good hand lens, you can often see the cystidia protruding from what looks like a flat surface), toothed, poroid or tuberculate (i.e. with lots of small, rounded bumps). They come in a range of colours and textures and are mostly wood rotters – with some that are mycorrhizal or parasitic species.

Corticioids are basidiomycetes with many of the microscopic features that you will be used to seeing in agarics and boletes. Thus basidia, spores, hyphae, clamps and cystidia are all important features that help us to distinguish one from another (More information on the different divisions within the kingdom of the fungi).

At first glance they appear impossible to differentiate and indeed you do need to use a microscope to really appreciate their beauty. Cylindrobasidium laeve is however common and quite distinct when it is young, forming round patches with a lovely pinkish brown centre fringed with white. These patches gradually coalesce into a larger structure and in some forms, the top edge grows outwards to form miniature brackets (effused – reflexed). The structure is soft and can be smooth to tuberculate and up to 1mm thick. Microscopically the species is distinguished by tear shaped spores (8-10 x 4-5) and the hyphae are usually full of oil droplets.

Fruiting

The majority of records in the UK occur between September and April but with a surprising lack of records for November in Scotland! This fits with the ecology of when the wood has a higher water content and the ground vegetation is lower, enabling corticioid species, many of which prefer to fruit on dead wood in the winter months, wind currents to circulate around the wood and, presumably, disperse spores.

Cylindrobasidium laeve just a little further on in development