|Major Groups > Boletes|
by Michael Kuo
Imagine taking the cardboard tube from a roll of paper towels, and affixing a lot of seeds to the inside of the tube. Then repeat the procedure with many other tubes, and glue them together. Suspend all the tubes from a board, so they hang downward—then wait for the seeds fall out. Somewhere along the long line of natural history, the boletes decided that this would be the most successful way to survive. Their caps look like the caps of the gilled mushrooms (a group that decided to hang seeds from sheets of cardboard, instead)—but, on the underside of the cap, there are tubes instead of gills. The tubes are so tightly packed that, from below, one sees only a pore surface composed of the openings of the tubes, looking rather like the surface of a sponge.
With very few exceptions, boletes are mycorrhizal partners with trees, and can be found in forest and urban ecosystems across our continent, wherever ectomycorrhizal trees are present. Some boletes are very picky about their mycorrhizal partners, while others seem to be able to associate only with groups of related trees—and still others may be able to associate with very diverse trees (although we may discover, as molecular study of the boletes evolves, that this last group is not nearly as big as we once thought).
There are a great many species of boletes, and identifying them ranges from relatively easy to profoundly difficult. In most cases you will need to have fresh mushrooms in front of you in order to be successful—preferably, specimens representing young and mature mushrooms. The morphology of a bolete's stem is often a good starting place for identification: look for scabers, glandular dots, or reticulation—and note the color of the basal mycelium. Other morphological features to examine carefully include the cap surface, the pore surface and tubes, the presence or absence of a veil, and the flesh. Many boletes have surfaces and/or flesh that discolor blue (or another color) when bruised or sliced. You will also frequently need to have a spore print available. In a few cases, odor or taste can be important. Chemical reactions can be very useful in identifying boletes; placing drops of ammonia, KOH, and iron salts on the cap surfaces and flesh of boletes can sometimes produce distinctive color reactions. Microscopic analysis of boletes is often required for identification; important characters include the morphology of spores and the pileipellis, along with cystidia in the tubes and on the stem. Finally, since boletes are mycorrhizal, noting what kind of tree is "hosting" your bolete can also be important information in the identification process.
At one time nearly all boletes were placed in the genus "Boletus." If you ask me, mycology should seriously consider returning to this strategy (at least for those genera now placed in the Boletinae), because what is evolving instead is a ridiculous display of career-making "splitting" based on each newly produced molecular phylogeny. Don't get me wrong; I am all for a naming system that actually reflects the way the organisms evolved and how they are phylogenetically related. I have no problem, for example, with including many of the bolete-related "false truffles," underground blobs, and miscellaneous what-nots in the same genera as the boletes they evolved with, despite their very different appearances. But DNA-based bolete taxonomy has taken the opposite route from, say, Cortinarius taxonomy, and has decided instead to name a new genus for virtually each new branch on the bolete tree—resulting in genus silliness like "Harrya" and "Sutorius," along with other taxonomic contortions. While contemporary bolete phylogenies make it clear that the traditional genus "Boletus" is entirely incoherent if we are going to have, for example, a "Leccinum" and a "Tylopilus" (all the comprehensive trees being produced these days show species of "Boletus" all up and down the branches, surrounding species from other genera, enabling no logical grouping), the answer to this problem does not have to be the creation of a new bolete genus for every day of the year. Humbly submitted; feel free, of course, to ignore it.
Regardless of how many bolete genera there are and whether the traditional genera (Boletus, Leccinum, Tylopilus, and so on) are "good," identification of the boletes is still greatly facilitated by the traditional characters. In other words, although DNA studies have shown us that we may not be able to justify separating a genus (Tylopilus) on the basis of a pinkish spore print and smooth spores, we can still handily separate a group of mushrooms for identification using these features. Thus the keys below rely on traditional morphological features—but they are, unfortunately, in varying states of "updatedness." Some of the older keys are very unsatisfactory; please accept my apologies and my promise that, when I can, I will revise them.
Keys to North American Boletes
Arora, D. (2008). California porcini: Three new taxa, observations on their harvest, and the tragedy of no commons. Economic Botany 62: 356–375.
Arora, D. & J. L. Frank (2014). Boletus rubriceps, a new species of porcini from the southwestern USA. North American Fungi 9: 1–11.
Arora, D. & J. L. Frank (2014). Clarifying the butter Boletes: a new genus, Butyriboletus, is established to accommodate Boletus sect. Appendiculati, and six new species are described. Mycologia 106: 464–480.
Ayala-Vásquez, O., R. Valenzuela, E. Aguirre-Acosta, T. Raymundo & J. García-Jiménez (2018). Species of Boletaceae (Boletales, Basidiomycota) with ornamented spores from temperate forests at the state of Oaxaca, Mexico. Studies in Fungi 3: 271–292.
Baroni, T. J. (1978). Chemical spot-test reactions—boletes. Mycologia 70: 1064–1076.
Baroni, T. J. & E. E. Both (1991). Chalciporus piperatoides in North America. Mycologia 83: 559–564.
Baroni, T. J., E. E. Both & A. E. Bessette (1998). Tylopilus rhodoconius, comb. nov.—new records, critical observations, illustrations, and notes on biogeography. Bulletin of the Buffalo Society of Natural Sciences 36: 257–260.
Baroni, T. J. & E. E. Both (1998). Tylopilus violatinctus, a new species of Tylopilus for North America, with comments on other violaceous colored Tylopilus taxa. Bulletin of the Buffalo Society of Natural Sciences 36: 261–264.
Bessette, A. E., E. E. Both, A. R. Bessette, D. L. Dunaway & W. C. Roody (1998). New taxa of boletes from the southern United States. Bulletin of the Buffalo Society of Natural Sciences 36: 233–237.
Bessette, A. E., Roody, W. C. & Bessette, A. R. (2000). North American boletes: A color guide to the fleshy pored mushrooms. China: Syracuse UP. 399 pp.
Beugelsdijk, D.C.M., S. van der Linde, G.C. Zuccarello, H.C. den Bakker, S.G.A. Draisma & M.E. Noordeloos (2008). A phylogenetic study of Boletus section Boletus in Europe. Persoonia 20: 1–7.
Binder, M. & H. Besl (2000). 28S rDNA sequence data and chemotaxonomical analyses on the generic concept of Leccinum (Boletales). In: Associazione Micologica Bresadola, ed. Micologia 2000. Brescia, Italy: Grafica Sette, 75–86.
Binder, M. & A. Bresinsky (2002). Retiboletus, a new genus for a species complex in the Boletaceae producing retipolides. Feddes Repertorium 113: 30–40.
Binder, M. & D. S. Hibbet (2006). Molecular systematics and biological diversification of Boletales. Mycologia 98: 971–981.
Both, E. E. (1993). The boletes of North America: A compendium. Buffalo NY: Buffalo Museum of Science. 436 pp.
Both, E. E. (1998). New taxa of boletes and two boletes with identity problems. Bulletin of the Buffalo Society of Natural Sciences 36: 215–232.
Both, E. E., S. Brown & B. Ortiz-Santana (2009). The second record of the European species, Boletus dupainii, in North America. Bulletin of the Buffalo Society of Natural Sciences 38: 1–4.
Both, E. E. & B. Ortiz-Santana (2010). Clinton, Peck and Frost—the dawn of North American boletology. Bulletin of the Buffalo Society of Natural Sciences 39: 11–28.
Both, E. E. & B. Ortiz-Santana (2012). An annotated index to species and intraspecific taxa of boletes (Mycota: Boletales: Boletaceae) in the Clinton Herbarium of the Buffalo Society of Natural Sciences. Bulletin of the Buffalo Society of Natural Sciences 41: 3–6.
Brundrett, M. C. & B. Kendrick (1987). The relationship between the ash bolete (Boletinellus merulioides) and an aphid parasitic on ash tree roots. Symbiosis 3: 315–320.
Bruns, T. D. & Palmer, J. D. (1989). Evolution of mushroom mitochondrial DNA: Suillus and related genera. Journal of Molecular Evolution 28: 349–362.
Coker, W. C. and Beers, A. H. (1943). The boleti of North Carolina. New York: Dover. 96 pp. (1971 reprint.)
Den Bakker, H. C., B. Gravendeel & T. W. Kuyper (2004a). An ITS phylogeny of Leccinum and an analysis of the evolution of minisatellite-like sequences within ITS1. Mycologia 96: 102–118.
Den Bakker, H. C., G. C. Zuccarello, T. W. Kuyper & M. E. Noordeloos (2004b). Evolution and host specificity in the ectomycorrhizal genus Leccinum. New Phytologist 163: 201–215.
Den Bakker, H. C. & M. E. Noordeloos (2005). A revision of European species of Leccinum Gray and notes on extralimital species. Persoonia 18: 511–587.
Den Baker, H. C., G. C. Zuccarello, Th. W. Kuyper & M. E. Noordeloos (2007). Phylogeographic patterns in Leccinum sect. Scabra and the status of the arctic-alpine species L. rotundifoliae. Mycological Research 111: 663–672.
Dentinger, B. T. M., J. F. Ammirati, E. E. Both, D. E. Desjardin, R. E. Halling, T. W. Henkel, P. -A. Moreau, E. Nagasawa, K. Soytong, A. F. Taylor, R. Watling, J. -M. Moncalvo & D. J. McLaughlin (2010). Molecular phylogenetics of porcini mushrooms (Boletus section Boletus). Molecular Phylogenetics and Evolution 57: 1276–1292.
Dick. E. A. & W. H. Snell (1965). Notes on boletes. XV. Mycologia 57: 448–458.
Frost, C. C. (1874). Catalogue of boleti of New England, with descriptions of new species. Bulletin of the Buffalo Society of Natural Science 2: 100–105.
García-Jiménez, J., F. Garza-Ocañas, J. I. de la Fuente, Á. E. Saldivar & O. Ayala-Vásquez (2019). Three new records of Aureoboletus Pouzar (Boletaceae, Boletales) from Mexico. Check List 15: 759–765.
Grand, L. F. & Smith, A. H. (1971). A previously unrecognized southern species of Boletus. Mycologia 63: 114–117.
Grand, L. F. & Smith, A. H. (1971). A new species of Boletus, section Luridi, from North Carolina. Mycologia 63: 884–888.
Grand, L. F. & Lodge, D. J. (1978). Occurrence of Boletus piedmontensis in North Carolina and Georgia. Mycologia 70: 1267–1268.
Grund, D. W. & Harrison, A. K. (1976). Nova Scotian boletes. Germany: J. Cramer. 283 pp.
Halling, R. E. (1977). California boletes VI. Some unreported species from the Sierra Nevada of California. Mycologia 69: 206–211.
Halling, R. E. (1983). Boletes described by Charles C. Frost. Mycologia 75: 70–92.
Halling, R. E. (1989). A synopsis of Colombian boletes. Mycotaxon 34: 93–114.
Halling, R. E. & E. E. Both (1998). Generic affinity of Boletus separans. Bulletin of the Buffalo Society of Natural Sciences 36: 239–243.
Halling, R. E. & Mueller, G. M. (1999). New boletes from Costa Rica. Mycologia 91: 893–899.
Halling, R. E. (1999). New Leccinums from Costa Rica. Kew Bulletin 54: 747–753.
Halling, R. E. & G. M. Mueller (2003). Leccinum (Boletaceae) in Costa Rica. Mycologia 95: 488–499.
Halling, R. E., T. W. Osmundson & M. A. Neves (2008). Pacific boletes: implications for biogeographic relationships. Mycological Research 112: 437–447.
Halling, R. E., M. Nuhn, T. Osmundson, N. Fechner, J. M. Trappe, K. Soytong, D. Arora, D. S. Hibbett & M. Binder (2012). Affinities of the Boletus chromapes group to Royoungia and the description of two new genera, Harrya and Australopilus. Australian Systematic Botany 25: 418–431.
Halling, R. E., M. Nuhn, N. A. Fechner, T. W. Osmundson, K. Soytong, D. Arora, D. S. Hibbett & M. Binder (2012). Sutorius: a new genus for Boletus eximus. Mycologia 104: 951–961.
Halling, R. E., N. Fechner, M. Nuhn, T. Osmundson, K. Soytong, D. Arora, M. Binder & D. Hibbett (2015). Evolutionary relationships of Heimioporus and Boletellus (Boletales), with an emphasis on Australian taxa including new species and new combinations in Aureoboletus, Hemileccinum and Xerocomus. Australian Systematic Botany 28: 1–22.
Hayward, D. & H. D. Thiers (1984). Gyrodon lividus in California. Mycologia 76: 573–575.
Hills, A. E. (2008). The genus Xerocomus: A personal view, with a key to the British species. Field Mycology 9: 77–96.
Hongo, T. (1974). Notes on Japanese larger fungi (21). Journal of Japanese Botany 49: 294–305.
Kibby, G. (2006) Leccinum revisited: a new synoptic key to species. Field Mycology 7: 77–87.
Knudsen, H. & A. Taylor (2008). Xerocomus Quél. In Knudsen, H. & J. Vesterholt, eds. Funga Nordica: Agaricoid, boletoid and cyphelloid genera. Copenhagen: Nordsvamp. 175–179.
Kretzer, A. et al. (1996). Internal transcribed spacer sequences from 38 recognized species of Suillus sensu lato: Phylogenetic and taxonomic implications. Mycologia 88: 776–785.
Klofac, W. (2010). The genus Aureoboletus, a world-wide survey. A contribution to a monographic treatment. Österreichische Zeitschrift für Pilzkunder 19: 133–174.
Kuo, M., A. S. Methven, A. M. Minnis & R. E. Halling (2013). Studies of North American macrofungi, 1. Validation of Lactarius rubidus comb. nov. and Leccinellum quercophilum sp. nov. Mycotaxon 124: 323–332.
Kuo, M. & B. Ortiz-Santana (2020). Revision of leccinoid fungi, with emphasis on North American taxa, based on molecular and morphological data. Mycologia 112: 197–211.
Lannoy, G. & A. Estades (1995). Monographie des Leccinum d’Europe. La Roche-sur-Foron, France: Federation Mycologique Dauphine-Savoie. 229 pp.
Lavorato, C. (2000). Suillus lakei var. calabrus var. nov. In: Associazione Micologica Bresadola, ed. Micologia 2000. Brescia, Italy: Grafica Sette, 285–288.
Lebel, T., T. Orihara & N. Maekawa (2012). The sequestrate genus Rosbeeva T. Lebel & Orihara gen. nov. (Boletaceae) from Australasia and Japan: a new species and new combinations. Fungal Diversity 52: 49–71.
Murrill, W. A. (1909). The Boletaceae of North America I. Mycologia 1: 4–18.
Nouhra, E., M. A. Castellano & J. M. Trappe (2002). NATS truffle and truffle-like fungi 9: Gastroboletus molinai sp. nov. (Boletaceae, Basidiomycota), with a revised key to the species of Gastroboletus. Mycotaxon 83: 409–414.
Nuhn, M. E., M. Binder, A. F. S. Taylor, R. E. Halling & D. S. Hibbett (2013). Phylogenetic overview of the Boletinae. Fungal Biology 117: 479–511.
Orihara, T., F. Sawada, M. Yamato, C. Tanaka, N. Shimomura, M. Hashiya & K. Iwase (2010). Taxonomic reconsideration of a sequestrate fungus, Octaviana columellidera, with the proposal of a new genus, Heliogaster, and its phylogenetic relationships in the Boletales. Mycologia 102: 108–121.
Orihara, T., M. E. Smith, Z. -W. Ge & N. Maekawa (2012). Rossbeevera yunnanensis (Boletaceae, Boletales), a new sequestrate species from southern China. Mycotaxon 120: 139–147.
Orihara, T., M. E. Smith, N. Shimomura, K. Iwase & N. Maekawa (2012). Diversity and systematics of the sequestrate genus Octaviana in Japan: two new subgenera and eleven new species. Persoonia 28: 85–112.
Ortiz-Santana, B., D. J. Lodge, T. J. Baroni & E. E. Both (2007). Boletes from Belize and the Dominican Republic. Fungal Diversity 27: 247–416.
Ortiz-Santana, B. & E. E. Both (2011). A preliminary survey of the genus Buchwaldoboletus. Bulletin of the Buffalo Society of Natural Sciences 40: 1–14.
Osmundson, T. W. & R. E. Halling (2010). Tylopilus oradivensis sp. nov.: a newly described member of the Tylopilus balloui complex from Costa Rica. Mycotaxon 113: 475–483.
Palm, M. E. & Stewart, E. L. (1984). Suillus neoalbidipes: A new species for Suillus albidipes. Mycologia 76: 433–438.
Palm, M. E. & Stewart, E. L. (1986). Typification and nomenclature of selected Suillus species. Mycologia 78: 325–333.
Petersen, R. H., K. W. Hughes, S. Adamcik, Z. Tkalcec & A. Mesic (2012). Typification of three European species epithets attributable to Strobilomyces (Boletales). Czech Mycology 64: 141–163.
Pomerleau, R. & Smith, A. H. (1962). Fuscoboletinus, a new genus of the Boletales. Brittonia 14: 156–171.
Redhead, S. A. & R. Watling (1979). A new psammophilic Leccinum. Canadian Journal of Botany 57: 117–119.
Selosse, M. A. (2003). Founder effect in a young Leccinum duriusculum (Schultzer) Singer population. Mycorrhiza 13: 143–149.
Singer, R. (1945). New Boletaceae from Florida (a preliminary communication). Mycologia 37: 797–799.
Singer, R. (1945). The boletinae of Florida. Germany: J. Cramer. 126 pp. (1977 reprint.)
Singer, R. (1978). Keys for the identification of the species of Agaricales I. Sydowia 30: 192–279.
Singer, R. & R. Williams (1992). Some boletes from Florida. Mycologia 84: 724–728.
Smith, A. H. & R. Singer (1959). Studies on secotiaceous fungi—IV: Gastroboletus, Truncocolumella, and Chamonixia. Brittonia 11: 205–223.
Smith, A. H. & Thiers, H. D. (1964). A contribution toward a monograph of North American species of Suillus. Ann Arbor: U Michigan. 116 pp.
Smith, A. H., Thiers, H. D. & Miller, O. K. (1965). The species of Suillus and Fuscoboletinus of the Priest River Experimental Forest and vicinity, Priest River, Idaho. Lloydia 28: 120–138.
Smith, A. H., H. D. Thiers & R. Watling (1966). A preliminary account of the North American species of Leccinum, Section Leccinum. The Michigan Botanist 5: 131–178.
Smith, A. H. & Thiers, H. D. (1967). Comments on Suillus amabilis and Suillus lakei. Mycologia 59: 361–367.
Smith, A. H., H. D. Thiers & R. Watling (1967). A preliminary account of the North American species of Leccinum, Sections Luteoscabra and Scabra. The Michigan Botanist 6: 107–154.
Smith, A. H. & Thiers, H. D. (1968). Notes on boletes—I. 1. The generic position of Boletus subglabripes and Boletus chromapes. 2. A comparison of four species of Tylopilus. Mycologia 60: 943–954.
Smith, A. H., H. D. Thiers & R. Watling (1968). Notes on species of Leccinum. I. Additions to Section Leccinum. Lloydia 31: 252–267.
Smith, A. H. & Thiers, H. D. (1971). The boletes of Michigan. Ann Arbor: U Michigan P. 428 pp.
Smith, A. H., Smith, H. V. & Weber, N. S. (1981). How to know the non-gilled mushrooms. Dubuque, Iowa: Wm. C. Brown. 324 pp.
Snell, W. H., A. H. Smith & L. R. Hesler (1940). New species of boleti from Cades Cove in the Great Smokies. Journal of the Elisa Mitchell Society 56: 325–328.
Snell, W. H. & E. A. Dick (1941). Notes on boletes. VI. Mycologia 33: 23–37.
Snell, W. H. & E. A. Dick (1961). Notes on boletes. XIV. Mycologia 53: 228–236.
Snell, W. H. & Dick, E. A. (1970). The boleti of northeastern North America. Germany: J. Cramer. 115 pp.
Šutara, J. (2008). Xerocomus s. l. in the light of the present state of knowledge. Czech Mycology 60: 29–62.
Taylor, A. F. S., A. E. Hills, G. Simonini, E. E. Both & U. Eberhardt (2006). Detection of species within the Xerocomus subtomentosus complex in Europe using rDNA-ITS sequences. Mycological Research 110: 276–287.
Thiers, H. D. & A. H. Smith (1966). An undescribed bolete in the B. rubellus group. The Michigan Botanist 5: 117–118.
Thiers, H. D. & J. M. Trappe (1969). Studies in the genus Gastroboletus. Brittonia 21: 244–254.
Thiers, H. D. (1971). California boletes. IV. The genus Leccinum. Mycologia 63: 261–276.
Thiers, H. D. (1975). The boletes of California (online reprint of California mushrooms: A field guide to the boletes). Retrieved February, 2020 from the MykoWeb website: http://www.mykoweb.com/boletes/index.html
Thiers, H. D. (1976). Boletes of the southwestern United States. Mycotaxon 3: 261–273.
Thiers, H. D. (1979). The genus Suillus in the western United States. Mycotaxon 9: 285–296.
Treu, R. (1993). Studies on Boletus Section Luridi. Mycotaxon 47: 367–377.
Vellinga, E. C., B. de la Houssaye, R. -L. Brace & V. Evenson (2006). Paragyrodon sphaerosporus: A Mid-western endemic? McIlvainea 16: 19–21.
Weber, N. S. & Smith, A. H. (1985). A field guide to southern mushrooms. Ann Arbor: U Michigan P. 280 pp.
Wells, V. L. & P. E. Kempton (1967). Studies on the fleshy fungi of Alaska. I. Lloydia 30: 258–268.
Wells, V. L. & P. E. Kempton (1975). New and interesting fungi from Alaska. Nova Hedwigia 51: 347–358.
Wolfe, C. B. (1979). Austroboletus and Tylopilus subgenus Porphyrellus with emphasis on North American taxa. Germany: J. Cramer. 148 pp.
Wolfe, C. B. (1981). Type studies in Tylopilus. I. Taxa described by Charles H. Peck. Sydowia 34: 199–213.
Wolfe, C. B. (1983). Taxonomic and nomenclatural notes on boletes. Mycotaxon 17: 398–404.
Wolfe, C. B. (1983). Type studies in Tylopilus. II. Taxa described by William A. Murrill. Mycologia 75: 699–706.
Wolfe, C. B. (1986). Type studies in Tylopilus. III. Taxa described by Walter H. Snell, Esther A. Dick, and co-workers. Mycologia 78: 22–31.
Wolfe, C. B. & R. E. Halling (1989). Tylopilus griseocarneus, a new species from the North American Atlantic and Gulf Coastal plain. Mycologia 81: 342–346.
Wolfe, C. B. (1990). Type studies in Tylopilus. IV. Taxa described by Rolf Singer. 1. Mycotaxon 38: 187–200.
Wolfe, C. B. (1991). Type studies in Tylopilus (Boletaceae). V. Taxa described by Alexander H. Smith, Harry D. Thiers, and Samuel J. Mazzer. Canadian Journal of Botany 69: 1833–1838.
Wolfe, C. B. & N. L. Bougher (1993). Systematics, mycogeography, and evolutionary history of Tylopilus subg. Roseoscabra in Australia elucidated by comparison with Asian and American species. Australian Systematic Botany 6: 187–213.
Wu, G., B. Feng, J. Xu, X.-T. Zhu, Y.-C. Li, N.-K. Zeng, Md. I. Hosen & Z. L. Yang (2014), Molecular phylogenetic analyses redefine seven major clades and reveal 22 new generic clades in the fungal family Boletaceae. Fungal Diversity 69: 93–115.
Zeng, N. -K., Z. -Q. Liang, G. Wu, Y. -C. Li & Z. L. Yang (2016). The genus Retiboletus in China. Mycologia 108: 363–380.
Zhang, M., T. -H. Li, M. Gelardi, B. Song & X. J. Zhong (2017). A new species and a new combination of Caloboletus from China. Phytotaxa 309: 118–126.
Zhang, M., T. -H. Li, C. -Q. Wang, N. -K. Zeng & W. -Q. Deng (2019). Phylogenetic overview of Aureoboletus (Boletaceae, Boletales), with descriptions of six new species from China. MycoKeys 61: 111–145.
Zhao, K., G. Wu, B. Feng & Z. L. Yang (2014). Molecular phylogeny of Caloboletus (Boletaceae) and a new species in East Asia. Mycological Progress 13: 1127–1136.
This site contains no information about the edibility or toxicity of mushrooms.
Cite this page as:
Kuo, M. (2013, December). The boletes. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/boletes.html