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Geoglossum nigritum

[ Ascomycetes > Helotiales > Geoglossaceae > Geoglossum ... ]

by Michael Kuo

The little black "Earth Tongues" of the Geoglossaceae family are a nightmare to identify--but if you are a microscope geek, they often reward you with fascinating and funky microscopic features. Geoglossum nigritum is among these mushrooms. To the naked eye, it is "distinct" in that its cap and stem are black, dry, and not finely velvety. This narrows things down to a handful of species--but you are not likely to get much further in the identification process without firing up the 'scope.

Geoglossum nigritum has amazing, septate (Mycologese for "partitioned by walls") spores that are packed side by side into its asci. The spores are almost always septate seven times (resulting in eight sections), and measure 54-85 µ long. Other defining microfeatures include the paraphyses (sterile cells between the asci), which are occasionally septate and have curved ends--and the fact that eight spores are packed into each ascus before they are shot out.


Ecology: Saprobic, on the ground in hardwood and conifer forests (sometimes growing on rotting wood); often found among mosses; growing alone or gregariously; summer and fall; widely distributed in North America.

Fruiting Body: Club-shaped, with a well defined head that is clearly separate from the stem and is often compressed or grooved; up to 8 cm high; black; the stem finely hairy, scaly, or nearly smooth, up to 2 mm thick.

Microscopic Features: Spores 54-85 x 6 µ; black or dark gray in KOH, dark brown in Melzer's; 7-septate or occasionally with more septa. Asci 8-spored; up to 18 µ wide. Paraphyses longer than the asci; cylindric; curved at the ends; occasionally septate but not constricted at the septa; brownish in Melzer's. Setae absent.

REFERENCES: (Persoon, 1801) Cooke, 1879. (Seaver, 1951; Smith, Smith & Weber, 1981.) Herb. Kuo 09120403.

Geoglossum fallax is dark brown. Geoglossum glutinosum and related species are slimy. Trichoglossum species are finely velvety.


Geoglossum nigritum

Geoglossum nigritum
Microscopic characters

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Kuo, M. (2005, January). Geoglossum nigritum. Retrieved from the MushroomExpert.Com Web site: