E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include 1) a large spherical to pear-shaped fruitbody, which develops a thick rooting base or stem, 2) peridium (skin) that is thin, brittle, usually "yellowish, purplish, olive-black, or brown", often lustrous, soon rupturing irregularly or flaking off to reveal the spore mass, 3) the spore mass containing hundreds of 0.2-0.4cm hard seed-like structures in a sticky dark substance that dries out, the whole spore mass eventually a crumbly mass of brown spores, 4) the lower part of the fruitbody typically persistent, with coarse greenish yellow to brownish fibers attached, 5) growth in waste places and other habitats, and 6) round spiny spores. Stains on the hands and clothing are to be expected when handling this fungus. It can be used as a dye producing mostly browns and golds, but also blacks and dark blues, depending on the mordants used and the type of soil in which it is found, (Arora). It is also used in Europe as an aromatic seasoning when unripe ("the Bohemian truffle"), and in China it is used medicinally, (Arora). Pisolithus arhizus also known as Pisolithus tinctorius and Polysaccum pisocarpium.

It is reported that based on intersterility tests and spores, there may be at least 3 biological species that fall under this name, the first from South Africa, the second from Australia, and the third from North America (including BC, MA, SC), Europe (France), and Australia, (Kope). It is very widely distributed but especially common in CA and the Pacific Northwest, (Arora). Oregon State University has collections from WA, OR, GA, MI, Dominican Republic, Mexico, Brazil, Morocco, India and Japan. The University of British Columbia has collections from BC, WA, FL, and LA.

Outer Surface:
4-20cm across, 5-30cm or more high, at first spherical to pear-shaped, then usually club-shaped (with narrowed rooting base or stem), finally breaking up when old "or taking on the appearance of a large dusty root or stump", peridium (skin) thin, brittle, "usually yellowish, purplish, olive-black, or brown", often lustrous, "soon ruptures irregularly or flakes away", (Arora), "ochraceous to dirty olive-brown and resembling balls of horse dung lying on the ground, with chrome yellow powdery markings on the submerged part", (Phillips), peridium dry, thin, smooth or faintly rugose [wrinkled] or tuberculate, at first ochreous then dark brown, (Lincoff(1))

Spore Mass:
upper part of fruitbody containing hundreds of seed-like peridioles that gradually disintegrate, turning into a crumbly or dusty mass of dark brown or cinnamon brown spores, the disintegrating process starting at the top of the fruitbody and proceeding downward; the peridioles 0.2-0.4cm long, elongated to oval or circular, whitish to greenish yellow, yellow, brownish, or vinaceous, at first embedded "in a sticky dark or blackish substance which dries out and becomes brittle or crumbly" when mature, (Arora), peridioles (pea-shaped chambers that contain the spores) stony, gravel-like, dark brown, (Phillips), flesh at the top of the spore mass when young compact, juicy, marbled, with violet-black peridioles with yellow outline, flesh in the sterile lower part "has, initially, a marbled appearance, brown, white, or deep yellow, with minute areolas, ochreous brown when mature", (Lincoff(1))

Stem:
lower part of fruitbody typically a fibrous, stem-like, persistent, sterile, rooting base that may have coarse greenish yellow mycelial fibers attached, (Arora), base 3-10cm in diameter, buried, solid, sturdy, often irregular, with (at first) a tuft of brown mycelial threads, (Lincoff(1))

Odor:
"mild to aromatic or unpleasant, depending on the age", (Arora), strong and pleasant mushroomy (Lincoff(1)), mild when young, unpleasant when old (Miller)

Taste:
sweetish (Lincoff(1))

Microscopic:
spores 7-12 x 7-12 microns, round, warty or spiny, (Arora), with coalesced spines (Kope), spores 7-9 microns in diameter excluding spines, round, coarsely spiny to warty, brown, (Buczacki)