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Species Information
Summary: Features include 1) a spherical to slightly flattened or depressed fruiting body often imbedded in white rhizomorphs, the rough outer surface whitish to grayish, often developing buff, pinkish, vinaceous, or brownish tints when old, 2) a peridium with a thin outer separable mycelial part and a thicker (0.3-0.5cm) inner part that is microscopically multilayered, 3) a spore mass that is white and soft, becoming sticky and blackish with a radial pattern, and finally black-powdery, 4) a conspicuous rounded columella in the middle of the spore mass, 5) clustered growth in soil or duff in woods (especially along roads in woods), and 6) microscopic characters including elliptic spores 5.6-7 x 4.2-5.5 microns, filiform 6-8-spored basidia, and specific peridial and glebal structures. Schenella simplex was originally thought to be a slime mold, but the name received priority when Radiigera atrogleba, described as a truffle, was later found to be the same species. In Schenella, dispersal by animals eating the fungus is supplemented by the development of spore-containing peridioles (radial sections of the spore mass) coated with a sticky substance, and in at least one species of the genus this enables parts of the spore mass to stick to the animal. It is abundant among false truffles in the Pacific Northwest (Trappe(13)).
Schenella simplex is found from BC to northern CA, ID, and CO, (Trappe(13)). Collections were examined from BC, WA, OR, ID, CA, CO, and UT, and it is also known from MT and Mexico, (Dominguez).
Outer Surface: 2.5-5cm broad, spherical to slightly flattened or depressed, "often imbedded in white mycelial threads (rhizomorphs)", peridium (skin) 3-layered, outer surface "tough and felty or fibrous-cottony, rough, white to grayish", often developing buff, pinkish, vinaceous, or brownish tints when old, "usually separating readily from the two inner layers"; inner two layers "closely adhering to each other, whitish to rosy or pinkish when fresh (but may turn olive or buff when bruised)", 0.3-0.5cm thick, "white when sectioned (or with a greenish tinge)", (Arora), 1-4cm across, spherical to nearly spherical; felty to cottony with adherent soil debris, outermost layer 0.02-0.05cm thick, yellow white to light yellow brown with some light pink hues, the layer underneath often exposed at maturity; endoperidium to 0.42cm thick, two-layered, the inner layer of 2 intergrading strata, tough, hard when dried, waxy to cartilaginous when rehydrated, (Dominguez), endoperidium of two layers, the outer about 0.1cm thick, the inner 0.3-0.4cm thick, (Smith(15) quoting Zeller)
Stem: "absent, but the basal portion of the peridium usually thickened slightly and giving rise to a prominent columella which is nearly round, cushion-shaped, or narrowed at base and enlarged (rounded) at the apex; columella usually 0.8cm thick or more at widest portion, usually penetrating the spore mass at least halfway (never percurrent); white or tinged gray, sometimes disintegrating in old age", (Arora), columella present (Dominguez)
Interior: "white, fleshy, and rather soft at first, becoming gooey or inky and blackish, and eventually powdery (and blackish)", (Arora), black at maturity, capillitium attached between peridium and columella, radial pattern apparent, (Dominguez)
Odor: often rather unpleasant in the inky stage (Arora), metallic, resembling that of actual ink, (Smith(15) quoting Gruber)
Microscopic: spores 5.5-6.5 microns, round, minutely warted, deep brown under microscope; interior "composed of plate-like bundles of hyphae which radiate from the columella to the peridium", (Arora), spores 5.6-7.0 x 4.2-5.5 microns, elliptic to rarely round in front and side view, round in polar view, finely verrucose, basal scar present, with apiculus; basidia 6-8-spored, to 28 x 1.5-2.5 microns, tubulose to filiform, with epibasidial part bearing short sterigmata (1 micron); gleba with long radiating locules when immature that form well-developed to poorly developed peridioles (radial sections containing spores and capillitial threads) at maturity; trama plate hyphae up to 1.5-2 microns wide, thin-walled; capillitium shiny, dark reddish brown, smooth, up to 7 microns diameter, attached to peridium and columella, persisting as tubes at maturity; columella of hyphae 2-5 microns wide, interwoven, colorless, "thin-walled, septate, clamped"; peridium 2-layered, to 4200 microns thick, a thin mycelial layer and a pseudoparenchymal layer, itself with 2 intergrading strata (and the thin outermost stratum itself with 2 zones): 1) the mycelial outer layer of the peridium is 175-200 microns thick, composed of hyphae 0.5-1 microns wide, entangled, flexuous [wavy], nonseptate, nonbranching, colorless, intermingled with soil debris, 2) the outer pseudoparenchymatous stratum is 42-100 microns thick, with an outer zone plectenchymatic lacking structure at maturity and inner zone of hyphae 2-4 microns wide, colorless, thin-walled, clamped, not reacting with cotton blue in lactic acid, and intermingled with conductive hyphae that are 2 microns wide, and react positively with cotton blue in lactic acid, the inner pseudoparenchymatous stratum is 2000-4200 microns thick, composed of thin-walled, colorless, inflated cells up to 60 microns in diameter, near the gleba the cells compressed and appearing almost flat, (a third stratum also sometimes present, "dark brown, undifferentiated, to 15 microns thick near the peridium, with attached capillitial threads"), (Dominguez), basidia 4-many spored (Smith(15) quoting Zeller)
Habitat / Range
single "or more often in groups or large, mycelium-incrusted clusters in soil or duff in woods and along old roads through the woods, usually buried or only partially exposed", mainly with conifers in summer or fall, (Arora), usually gregarious, under conifers, May to November, most often August through October, (Dominguez), in closely connected, almost ingrown, clusters of 15-30, deep in the soil with only a few visible, (Smith(15) quoting Gruber), probably saprotrophic (Trappe(13))
Similar Species
Geastrum taylorii is smaller with a smoother brownish to drab exterior, and a paler brown spore mass. Geastrum fuscogleba has an olive-brown to brown mature spore mass and spiny spores. Compare also with Geastrum bushnellii and Schenella pityophilus.
