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

Summary:
{See also Earthstars Table.} Geastrum schmidelii is "at once distinguished in the field by the strongly sulcate peristome, by the short pedicel of the spore sac, and by its not being fornicate when fully expanded" (Smith(49)). Other features include relatively small size, 4-8 non-hygroscopic rays, and persistent outer mycelial layer from the rays that encrusts debris. Note the discrepancy in spore size among descriptions.

A collection from BC, collected by A. McKinnon and determined by P. Kruger, is at the University of British Columbia (as Geastrum nanum). RANGE Geastrum schmidelii was examined from NJ, NC, NE, TX, VA, and Cuba, (Coker), and MI (Smith(49)).

Outer Surface:
underground at first, more or less spherical "to depressed or ovate, rarely umbonate", "strongly encrusted with sand and debris", 1.4-3.7cm across when expanded, as 5-8 non-hygroscopic rays split to about half way, "arched and somewhat recurved or almost horizontal"; outermost mycelial layer of rays "persistent, strongly encrusting sand and debris", middle fibrous layer of rays "papery, whitish to pale yellowish brown", innermost pseudoparenchymatous layer of rays whitish becoming pale brown, darkening when old "and usually dark brown in dried specimens", (Pegler), 0.5-0.8cm in diameter when unopened, spherical with a bluntly conic apex; pallid and with adhering debris, outer wall splitting into 4-6 rays "which spread out into a horizontal or slightly recurved position"; mycelial layer persistent causing debris to remain on underside of rays; "fibrous layer very thin in dried specimens; fleshy layer also thin, continuous out over surface of rays or in drying cracking at juncture of rays and base of fruiting body, pallid to pale brownish", (Smith(49))

Inner layer:
spores case more or less spherical to ovate or depressed, gray-brown to clay-colored, "often minutely white-pruinose when fresh, becoming smooth"; peristome [mouth] "usually distinctly delimited by a low, circular ridge" and paler than the surrounding spore case, usually acutely conic, 0.2-0.4cm high, plicate [pleated], mostly with 14-20 ridges, (Pegler), "spore case ovate to globose-pedicellate with a long conic peristome; surface pallid to brownish drab (in oldest specimen), papery, unpolished to covered with a whitish bloom; mouth strongly sulcate, grading indistinctly into tissue of spore sac or obscurely delimited by a depression", (Smith(49))

Spore Mass:
dark brown when mature; columella "small and rather weakly developed, rounded to narrowly clavate", (Pegler), chocolate brown (Smith(49))

Stem:
spore case short-stalked (Pegler), stalk of spore case short (Smith(49)), very short-stalked (Coker(3))

Microscopic:
spores 4.8-5.6 microns wide, excluding ornamentation, 5.6-6.5 microns in diameter including ornamentation, round, verruculose, verruculae irregular, often coalescent, 0.3-0.7 microns high, 0.3-1.5 microns across; basidia not seen; capillitial hyphae 2-6 microns wide, pale brown to yellow-brown or almost colorless, "thick-walled, with a narrow, discontinuous lumen", gradually and finely tapered to rounded or subacute tips 1-2.5 microns in diameter, irregularly encrusted, (Pegler), spores 3.5-4.2 microns in diameter, round with a thin colorless envelope "into which slightly colored warts project", near bister under the microscope; capillitium pallid to slightly yellowish in iodine, threads 3-6 microns wide with very thick walls, (Smith(49)), spores 3.7-4.6 microns in diameter, round, warted, with a visible oil droplet, (Coker)