Summary:
Distinctive characters are the basic pale yellow color when fresh, a rapid dark blackish green reaction of the dried surface and spore mass to FeSO4, a red reaction of the dried surface to KOH which soon fades to rusty brown, narrow spores, and a lack of thick-walled hymenial elements, (Smith(30)). A more complete list of features is 1) a spherical to lobed fruitbody with the surface cream to yellowish and finally yellowish tan to olive brown, bruising pink to red-brown, 2) whitish brownish rhizomorphs that when young bruise pinkish, 3) a basal cluster of rhizomorphs, 4) a spore mass that is cartilaginous, pallid to yellowish then olive gray to olive-brown or yellow-brown, 5) a rapid dark blackish green reaction of the dried surface and spore mass to FeSO4, 6) a red reaction of the dried surface to KOH which soon fades to rusty brown, 7) underground growth under conifers, 8) smooth spores that are narrowly subfusoid or elliptic or oblong, 9) 4-spored and 8-spored basidia, 10) a lack of thick-walled hymenial elements, 11) a peridial epicutis that is a turf of spherical to ovoid, thin-walled, inflated cells, and 12) a peridial subcutis with oleiferous hyphae and orange brown to reddish brown pigment. It is abundant among false truffles in the Pacific Northwest (Trappe(13)).

Chemical Reactions:
for dried collections, surface and spore mass quickly dark blackish green in FeSO4, surface red in KOH but the red soon fading to rusty brown, (Smith(30)), FeSO4 on white peridium dull grey to blackish grey, negative on older surface, negative on spore mass, KOH on white surface reddish white, on yellow or olive areas brown, KOH negative on spore mass, (Miller)

Interior:
"pallid then olive gray"; cartilaginous when fresh, sectioning readily when dried, (Smith(4)), soft; white at first, becoming greenish and finally olive-brown; with narrow maze-like chambers, (Lincoff), pallid almost to maturity; chambers empty; deliquescent when mature, (Smith(30)), soft, cake-like at first, then tough, cartilaginous, when old gelatinous; white to yellowish white or pale yellow when young, then olive yellow, finally olive brown to yellowish brown, "often mottled light to dark because of erratic maturation", young specimens with pale spore mass occasionally bruising pinkish white, when dried grayish yellow to yellowish brown, (Miller), white when young, light olive by maturity, (Trappe, M.(3))

Odor:
slight (Smith(4)), slightly acid and fruity then acrid and penetrating (Lincoff), faint, like Scleroderma, or in some mature specimens strong and offensive, (Smith(30)), similar to the commercial mushroom when fresh, when old strongly of road tar, (Miller)

Taste:
initially sweet (Lincoff), mild (Trappe, M.(3))

Microscopic:
spores 5.5-8 x 2-2.6 microns, many subfusoid; "peridium of appressed hyphae, no pockets of vesiculose cells seen, in KOH finally fulvous near the surface" and nearly colorless toward the spore mass, with copious pigment in peridium as revived in KOH, (Smith(4)), spores 5-8 x 2-3 microns, elliptic, smooth, whitish, (Lincoff), spores 5.5-8 x 2-2.6 microns, narrowly subfusoid to elliptic varying to oblong, smooth, in Melzer''s reagent yellowish singly and in groups, in KOH colorless singly and yellowish in groups, with inconspicuous basal scar; basidia 4-spored and 8-spored, 14-17 x 4-5 microns, "subcylindric, readily collapsing"; paraphyses 10-18 x 4-10 microns, subspherical to clavate or vesiculose and thin-walled; cystidia none; "subhymenium poorly developed and individual cells indistinct in revived material"; tramal plates "with gelatinous highly refractive hyphae more or less interwoven"; peridium of "appressed-interwoven hyphae at first red in KOH but soon fading out to fulvous and with orange-brown pigment globules in upper region (in Melzer''s sol.), no pockets of vesiculose cells noted", the part next to the gleba finally nearly colorless; all tissues inamyloid; clamp connections none, (Smith(30)), spores 7.5-9.5(10.5) x 2.5-3.0 microns, subcylindric, oblong to narrowly subfusoid, often slightly curved in side view, in Melzer''s reagent pale yellow singly, dull olive yellow in mass, mostly with 2-3 lipid droplets, in KOH pale yellow singly, dull yellowish gray in mass, basal scar present but not prominent; basidia borne in a distinct hymenium, 12-18 x 4-5 microns, subcylindric to narrowly clavate, "thin-walled and soon collapsing, mostly 8-spored", brachybasidioles 10-20 x 6-10 microns, subspherical, clavate, or obovate, thin-walled when young, thick-walled, mucilaginous when old, not readily disarticulated in crush mounts; subhymenium poorly developed, composed of branching, colorless, thin-walled or thick-walled, cylindric or cubic hyphae; trama of hyphae that are 4-7 microns wide, colorless, highly refractive in KOH, cylindric to slightly swollen, thin-walled when young, mucilaginous when old, oleiferous hyphae present in mediostratum, 6-12 microns wide, hyaline refractive to deep yellow in KOH and in Melzer''s reagent, "cylindric or irregularly swollen and contorted"; peridium 300-360 microns thick, peridial subcutis a layer of hyphae that are 6-14 microns wide, cylindric, appressed, interwoven, and thin-walled, oleiferous hyphae abundant, 8-20 microns wide, dark yellowish brown in KOH and in Melzer''s reagent, cylindric or irregularly swollen and contorted, occasionally branching, slightly gelatinized when old, "lightly encrusted with amorphous pigment that is orange brown to reddish brown in KOH, orange brown in Melzer''s reagent, readily liquefying into large, compound orange brown pigment globules", peridial epicutis a turf of spherical to ovoid, thin-walled, inflated cells; clamp connections absent, (Miller)

Notes:
Collections were examined from OR, AR, CA, FL, MA, MS, TN, and VA, (Miller). Collections were examined from BC (although paraphyses were thick-walled), ID, NS, and TN, (Smith(30) saying that they are tentatively assigned here). It is found in ID (rare) according to Smith(4). It was reported from WA by Colgan(2). Besides being found in the Pacific Northwest, it is widespread in the United States and Europe, (Trappe(13)). It is found in the United Kingdom (Hawker(1)).

EDIBILITY

edible when immature, but too difficult to identify accurately (Lincoff for Europe)