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

Summary:
Features include 1) a cup-shaped to flattened fruitbody with the upper surface dark brown to black, and the underside the same color or paler, 2) absent stem, 3) growth on burnt ground, and 4) microscopic characters including smooth spores.

Plicaria endocarpoides is found at least in BC, WA, OR, ID, CA, and MT, (Larsen), New Zealand and the United Kingdom, (Dennis), and Denmark, Finland, and Norway, (Hansen).

Upper surface:
1-7cm across, "at first cup-shaped but soon becoming flattened or undulating"; spore-bearing upper surface dark brown to black, smooth or rough, sometimes wrinkled, (Arora), reaching 2-3cm across, at first spherical expanding to shallow cup-shaped, regular or cochleate and occasionally incised and Otidea-like, finally scutellate or somewhat disc-shaped; upper surface reddish brown to brownish black with slight olive tinge, smooth and even or undulating and lobed, (Seaver), up to 7cm across, cup-shaped then spreading flat, upper surface dark brown, (Tylutki), 2-8cm across, cup-shaped, upper surface dark grayish brown to brown, (Hansen)

Flesh:
rather brittle; "usually paler or browner than the upper surface", (Arora), brittle (Tylutki), thin (Hansen), becoming yellowish when cut and exuding a yellow juice, (Dennis)

Underside:
same color as upper surface or paler; smooth or roughened, (Arora), reddish brown to brownish black with slight olive tinge, a little lighter than upper surface; often strongly roughened, (Seaver), paler than upper surface, smooth, (Tylutki), grayish brown; bald or delicately furfuraceous in upper part, (Hansen)

Stem:
absent or rudimentary, (Arora)

Microscopic:
spores 8-10 microns in diameter, "round, smooth, typically with several small oil droplets", (Arora), spores reaching 10-12 microns in diameter, smooth, colorless or slightly yellowish, rather thick-walled, usually containing one large central oil droplet, 2-seriate becoming 1-seriate; asci reaching a length of 350 microns and a diameter or 15-18 microns, cylindric or subcylindric in upper part, tapering in lower part into stem-like base; paraphyses, slender, rather abruptly widened in upper part, densely granular within, reaching width of 7 microns, showing a tendency to stick together in bundles, (Seaver), spores 8-10 microns in diameter, round, smooth, with granular contents; asci 190-200 x 9.5-11 microns, J+; paraphyses filiform [thread-like], slightly expanded at tip, up to 4 microns wide and covered by an amorphous yellow-brown incrustation; medullary excipulum of textura globulosa and filamentous cells, up to 2 microns wide, ectal excipulum of textura globulosa, the cells smaller than in medullary excipulum, (Tylutki), spores 8.5-9.5 microns in diameter, smooth, (Hansen), spores 8-9 microns in diameter, smooth, colorless or faintly brownish, containing numerous small oil droplets, (Dennis)