A lumpy, club- to top-shaped earthball-like fungus whose cut interior shows pea-sized spore packets set in a blackish gel; these break down from the top into cinnamon brown spore dust. It is an important ectomycorrhizal partner of pines and hardwoods on poor, sandy or disturbed ground and has long been used as a dye. North American guides call it P. tinctorius or P. arhizus, but MushroomExpert, following Martin et al. (2002) and Lebel et al. (2018), applies P. arenarius to North American material.
Not edible. Sources disagree about whether Pisolithus is harmful, and it is regarded as unsafe to eat; it is also hard, gelatinous and gritty inside and may take up pollutants from the soil it grows in. Young specimens could be confused with earthballs (Scleroderma, poisonous), which have a uniform dark interior without separate peridioles.
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Habitat
Ectomycorrhizal with pines and various hardwoods, including oaks; alone, scattered or in small groups in gravel, sandy soil, roadsides, ditches, lawns and disturbed or mine-reclaimed ground. Summer and fall, or over winter in warm climates.
Distribution
Widely distributed in North America, more common on the West Coast and in the Southeast; well documented from the San Francisco Bay Area, the northern Sierra Nevada, the New Jersey Pine Barrens and Cape Cod. True P. arhizus appears to be limited to Europe, Africa and Asia.
Characteristics
Fruitbody: 4-10 cm high, 3-8 cm across; ball-shaped when young, with or without a stubby stemlike base, stretching with age into top-, stump- or cylinder-shaped forms; yellowish rhizomorphs often attached. Surface: brownish to yellowish, thin and fragile, eventually breaking up. Interior: pea-sized peridioles, yellow to whitish or cinnamon brown, in a blackish gel, maturing from the top down into powdery spore mass. Odor: not distinctive. Spore print: cinnamon brown. Spores: 5-8 um excluding ornament, globose, thick-walled, densely spiny with spines 1-2 um long (MushroomExpert).
