Major Groups > Puffballs & Others > Pisolithus arenarius


Pisolithus arenarius

[ Basidiomycota > Boletales > Sclerodermataceae > Pisolithus . . . ]

by Michael Kuo

This amazing mushroom starts out looking like a tough, walnut- to baseball-sized puffball, but eventually develops into a minor monstrosity that sticks up from the ground like a dusty stump. The thing is so strong that it regularly erupts through asphalt, as in the second and third illustrations. When young its interior is filled with pea-sized spore packages ("peridioles") embedded in a blackish ooze, but these begin to disintegrate from the top down and the thin outer rind breaks apart to expose the interior, releasing spores; often the area surrounding Pisolithus arenarius is covered with cinnamon brown spore powder.

Your North American field guide probably calls the mushroom featured here "Pisolithus tinctorius" or "Pisolithus arhizus"—but recent research (Martin et al. 2002, Lebel et al. 2018) indicates that Pisolithus arenarius is a more appropriate name, since 1) Pisolithus arhizus appears to be limited to Europe, Africa, and Asia, and 2) the name Pisolithus tinctorius, in the sense it has been traditionally applied, is officially illegitimate because Coker and Couch (1928) applied it without knowing it had already been used (Fischer 1900), for a species associated with rockroses on the Canary Islands. For a more detailed accounting of this nomenclatural conclusion, see Lebel and collaborators (2018).

Contemporary studies of Pisolithus have been primarily focused on European and Australasian collections; our North American versions demonstrate considerable variability in their physical features and mycorrhizal hosts (see Grand 1976) and, once the Great Eye of DNA Sauron turns to our continent, a shake-up may well result.

Thanks to Penny Firth and Matthew Felix for collecting, documenting, and preserving collections of Pisolithus arenarius for study; their collections are deposited in The Herbarium of Michael Kuo.


Ecology: Mycorrhizal with various hardwoods and pines; growing alone, scattered, or in small groups; often found in gravel, sandy soil, in ditches, on lawns, and so on; summer and fall, or over winter in warm climates; widely distributed in North America but more commonly found on the West Coast and in the southeast. The illustrated and described collections are from California, Kentucky, and Virginia.

Fruiting Body: 4–10 cm high; 3–8 cm across; ball-shaped when young, with or without a stemlike base; stretching out with maturity to become top-shaped, tooth-shaped (like a giant molar), stumplike, widely cylindric, or just plain odd; outer surface at first brownish to yellowish, eventually breaking up to expose the interior; outer rind thin and fragile; interior at first packed with pea-sized, yellow to whitish or cinnamon brown spore packages embedded in blackish gel, disintegrating from the top downward to become a mass of cinnamon brown spore dust (often gelatinous toward the base); stem-like base when present rudimentary and stubby; often with yellowish rhizomorphs attached.

Odor: Not distinctive.

Spore Print: Cinnamon brown.

Microscopic Features: Spores 5–8 µm excluding ornamentation; globose; densely echinate with isolated spines 1–2 µm long and about 0.5 µm wide at the base; thick-walled; golden in KOH.

REFERENCES: Albertini & Schweinitz, 1805. (Coker & Couch, 1928; Smith, 1951; Grand, 1976; Burk & Lupone, 1979; Smith, Smith & Weber, 1981; Weber & Smith, 1985; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Metzler & Metzler, 1992; Horn, Kay & Abel, 1993; Cairney, 2002; Martin et al., 2002; Miller & Miller, 2006; Kuo & Methven, 2010; Phosri et al., 2012; Desjardin, Wood & Stevens, 2015; Siegel & Schwarz, 2016; Baroni, 2017; Elliott & Stephenson, 2018; Lebel et al., 2018.) Herb. Kuo 08111212, 08131801, 09201801.

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Pisolithus arenarius

Pisolithus arenarius

Pisolithus arenarius

Pisolithus arenarius

Pisolithus arenarius

Pisolithus arenarius

Pisolithus arenarius

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Kuo, M. (2018, December). Pisolithus arenarius. Retrieved from the MushroomExpert.Com Web site: