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The Genus Gomphidius  

[ Basidiomycota > Boletales > Gomphidiaceae . . . ]

by Michael Kuo

The mushrooms in Gomphidius are slimy-capped conifer lovers with dark gray to black spore prints, gills that run down the stem, and stems that are often—though not always—bright yellow near the base. The flesh in the cap and stem is white, and observation of this feature is sometimes the best way to separate species of Gomphidius from species of Chroogomphus, which can appear similar but feature orangish to yellowish or reddish flesh.

Although species of Gomphidius have gills rather than pores, they have evolved with the boletes in the Boletales, near the genus Suillus—which is perhaps not a big surprise, since species of Suillus are the slimy conifer lovers among boletes.

Identification of Gomphidius collections can often be accomplished without reference to microscopic features by paying careful attention to cap colors, whether or not the stem is bright yellow toward the base, and whether or not a "slime veil" covers the young gills. The slime veil itself can be observed in button-stage specimens, but its presence can later be deduced, after the veil itself has broken, by the presence of slime on the stem. When microscopic examination is required for Gomphidius identification, it usually involves simple measuring of mature spores.


Gomphidius smithii

Gomphidius glutinosus

Key to 10 Gomphidius Species in North America  

1.With a slime veil covering the young gills, leaving thick slime on the stem as the cap expands.

1.Without a slime veil; stem not slimy.

2.Mature stem not bright yellow at the base.

2.Mature stem bright yellow at the base or nearly overall.

3.Typically growing in clusters, often with stem bases fused; stem base often rooting; spores 10–14 µm long; known only from western North America.

3.Not usually growing in clusters with stem bases fused; stem base not usually rooting; spores longer than 14 µm; variously distributed.

4.Cap pinkish to dull reddish; stem 0.5–1.5 cm wide.

4.Cap more or less brown or dark purplish gray, blackening with age; stem 1–2 cm wide or more.

5.Cap 3–10 cm across; northern and montane in distribution.

5.Cap up to 20 cm across; growing at high elevations.
Gomphidius largus

6.Young cap whitish to yellowish; stem blackening on handling; associated with eastern white pine in eastern North America.
Gomphidius nigricans

6.Young cap more highly colored; stem not blackening; mycorrhizal associations and distributions varying.

7.Spores shorter than 14 µm; known from Idaho.
Gomphidius pseudomaculatus

7.Spores longer than 14 µm; distribution varying.

8.Spores shorter than 23 µm; lower stem covered with smoky yellow to purplish black fibers.
Gomphidius maculatus

8.Many spores longer than 23 µm; lower stem not as above.

9.Spores 18–29 µm long; found in northern conifer bogs and with red spruce in the Appalachians.
Gomphidius flavipes

9.Spores 18–40 µm long; known from spruce-pine woods in Fresno County, California.
Gomphidius pseudoflavipes


Kauffman, C. H. (1925). The genus Gomphidius in the United States. Mycologia 17: 113–126.

Miller, O. K. Jr. (1971). The genus Gomphidius with a revised description of the Gomphidiaceae and a key to the genera. Mycologia 63: 1129–1163.

Miller, O. K. Jr. et al. (2002). Two new species of Gomphidius from the western United States and eastern Siberia. Mycologia 94: 1044–1050.

Miller, O. K. Jr. (2003). The Gomphidiaceae revisited: a worldwide perspective. Mycologia 95: 176–183.

Singer, R. (1949). The genus Gomphidius Fries in North America. Mycologia 41: 462–489.

Thiers, H. D. (1985). The Agaricales of California. 3. Gomphidiaceae. Eureka, CA: Mad River Press. 20 pp.

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Cite this page as:

Kuo, M. (2014, February). The genus Gomphidius. Retrieved from the MushroomExpert.Com Web site:

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