Geoglossum Pers.
(black earthtongues)

A small group of black ascomycetes which grow in grassland. Many species are restricted to unimproved grassland, but their use as indicator species is limited as they can grow in mixed troups and need to be individually determined under the microscope.

The diagnostic features (ascospores, paraphyses) are microscopic, and require a ripe fruitbody, so not every specimen will be identifiable.

Ripe ascospores are dark grey (in most species) and multiseptate and will normally be abundant in the preps. Different parts of the fruitbody may be at different stages of ripeness, so try a second sample before giving up.

The different species of Earth Tongues are more or less indistinguishable in the field. As they often grow in mixed groups, they have to be individually identified, back in the lab. When sampling a site, it’s best to collect a range of specimens with different shapes and from different patches to maximise the chance of sampling all the species and getting some mature fruitbodies.

A quick way to screen for ripe fruitbodies is to lay them out on white paper and cover them for an hour. The ripe fruitbodies will be surrounded by a halo of black spores.

The ascospores are best viewed in Lactophenol, as this removes confusing oil globules (AJS), but dilute Ammonia is better for the paraphyses as they separate better in this reagent (MWS). Melzer’s is good too (MWS).