Geoglossum cookeanum

Description

Geoglossum cookeanum is a mushroom in the family Geoglossaceae. It is characterized by its robust non-gelatinized fruit bodies, paraphysis tips with chains of dark brown inflated ovoid to doliiform cells, and ascospores that are almost always 7-septate. This fairly common earthtongue fungus is found mainly in mossy, sandy grassland, often in dune slacks or on the edges of coastal pine forests.

Mushroom Identification

1. Fruit Body

   Stromata is black, club-like, comprising a longitudinally indented fertile section above a more or less cylindrical infertile stem. The fertile section, shaped like a flattened club, covers the upper 50 to 70% of the fruitbody and is finely scurfy. Individual tongues are typically 3 to 7cm tall.

2. Asci

   Cylindrical, 140-180 x 16-18µm; fairly thick-walled; 8-spored.

3. Spores

   Ascospores elongated cylindrical to fusiform with an acute base and a rounded apex; fairly thick-walled; smooth, 55-90 x 5-7µm; multiseptate (very occasionally 6-septate but usually 7-septate).

4. Spore Print

   Light brown.

5. Paraphyses

   Borne in separate clusters are diagnostic of this species. Filiform, 2-3µm in diameter and extending slightly beyond the asci tips; not curved or coiled at the apex; base section hyaline and upper parts pale to mid-brown with thicker walls and increasingly more closely septate towards tips, which comprise a chain of doliform to ovoid cells 4-6µm in diameter.

6. Odor and Taste

   Not distinctive.

7. Habitat & Ecological Role

   On the ground in unimproved grassland and mossy dune slacks.

Look-Alikes

1. Xylaria polymorpha

   Is an ascomycete of similar size. It grows on dead hardwood and its stromata (compound ascomycetous fruitbodies) are not usually laterally compressed or indented.

2. Trichoglossum hirsutum

   Has a stem that is minutely hirsute rather than scaly.

History

This sombre earthtongue species was described in 1942 by Swedish botanist and mycologist John Axel Nannfeldt (1904 - 1985), who gave it the scientific binomial name Geoglossum cookeanum. Some authorities include an 'i' is the specific epithet, thus making Geoglossum cookeianum.

The genus Geoglossum, set up by Christian Hendrik Persoon in 1794, is named from Geo- meaning earth and -glossum meaning tongue - hence fungi in this genus are referred to as earthtongues (or, as some authors prefer to write it, earth tongues). The specific epithet cookeanum honors the famous British mycologist Mordecai Cubitt Cooke.

Photo sources:

Photo 1 - Author: bjoerns (CC BY-SA 4.0)

Photo 2 - Author: bjoerns (CC BY-SA 4.0)

Photo 3 - Author: bjoerns (CC BY-SA 4.0)