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The Genus Hebeloma
by Michael Kuo
Hebeloma is a large, confusing genus of brown-spored, gilled mushrooms that range considerably in their physical features. The species are mycorrhizal with a wide range of trees, and can be found in most woodland ecosystems on our continent.
Many species of Hebeloma have a veil that can be reminiscent of the cortina in Cortinarius--but the veil, when present, is often ephemeral, and many species lack the veil entirely. The spore print is brown or pinkish brown. The edges of the gills are often whitish, contrasting with the brownish gill faces. In many species the apex of the stem is mealy or very finely scaly--and in many species the odor of the crushed flesh is pronounced and radishlike. Under the microscope, species of Hebeloma have warty spores that are often flask- or lemon-shaped, abundant cheilocystidia, and a gelatinized pileipellis.
Identification of species in Hebeloma is tedious, and microscopic study of specimens is required; a Roman aqueduct section is the place to start. Beyond a few of the well known "field guide species" (which are actually species groups), most of the genus consists of groups of frustratingly similar mushrooms, and a would-be Hebeloma identifier is quickly subsumed in painstaking analysis of the morphology of cheilocystidia.
DNA studies of Hebeloma, so far, have basically supported the concept of the genus that has reigned for decades--along with many of the subgeneric divisions mycologists have erected. Individual species, however, may need to be redefined in several cases. But contemporary study of the genus has focused on Europe (especially northern Europe), and North American material has yet to be considered with any sustained focus. Some of the DNA-based work that has been done (Aanen and collaborators, 2000; Eberhardt and collaborators, 2009) has supported the idea that at least some species in the genus are particular about their mycorrhizal associations, and are limited to certain hosts or host groups.
Aanen, D. K. & T. W. Kuyper (1999). Intercompatibility tests in the Hebeloma crustuliniforme complex in northwestern Europe. Mycologia 91: 783-795.
Aanen, D. K., T. W. Kuyper, T. Boekhout & R. F. Hoekstra (2000). Phylogenetic relationships in the genus Hebeloma based on ITS1 and 2 sequences, with special emphasis on the Hebeloma crustuliniforme complex. Mycologia 92: 269-281.
Aanen, D. K. & T. W. Kuyper (2004). A comparison of the application of a biological and phenetic species concept in the Hebeloma crustuliniforme complex within a phylogenetic framework. Persoonia 18: 285-316.
Beker, H. J., U. Eberhardt & J. Vesterholt (2010). Hebeloma hiemale Bres. in artic/alpine habitats. North American Fungi 5: 51-65.
Boyle, H., B. Zimdars, C. Renker & F. Buscot (2006). A molecular phylogeny of Hebeloma species from Europe. Mycological Research 110: 369-380.
Eberhardt, U., H. J. Beker, J. Vila, J. Vesterholt, X. Llimona & R. Gadjieva (2009). Hebeloma species associated with Cistus. Mycological Research 113: 153-162.
Grilli, E. (2000). Studies on the genus Hebeloma. Bresadola's conception of Hebeloma elatum (Batsch: Fr.) Gillet. In: Associazione Micologica Bresadola, ed. Micologia 2000. Brescia, Italy: Grafica Sette, 231-240.
Miller, O. K. Jr. & V. S. Evenson (2001). Observations on the alpine tundra species of Hebeloma in Colorado. Harvard Papers in Botany 6: 155-162.
Mondiet, N., M.-P. Dubois & M.-A. Selosse (2007). The enigmatic Squamanita odorata (Agaricales, Basidiomycota) is parasitic on Hebeloma mesophaeum. Mycological Research 111: 599-602.
Smith, A. H., V. S. Evenson & D. H. Mitchel (1983). The veiled species of Hebeloma in the western United States. Ann Arbor: University of Michigan Press. 219 pp.
Smith, A. H. (1984). Studies of species of Hebeloma (Fr.) Kummer from the Great Lakes region of North America I. Sydowia 37: 271-283.
Vesterholt, J. (2005). The genus Hebeloma. (Fungi of Northern Europe, Vol. 3). Denmark: The Danish Mycological Society. 146 pp.
Cite this page as:
Kuo, M. (2012, March). The genus Hebeloma. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/hebeloma.html