What You Should Know
Geastrum coronatum is an inedible species of mushroom belonging to the genus Geastrum, or earthstar fungi. Earthstars all look much the same until you examine them closely. No conclusion can be drawn from the number of rays, as they are very variable. The shape and coloring of the opening at the top of the spore sac plus the attachment of the spore sac to the outer layer that forms the rays are key features.
Other names: Crowned Earthstar.
Geastrum coronatum Mushroom Identification
Fruiting body subglobose, 1.5-3.0 cm broad, hypogeous, then erumpent; exoperidium non-hygroscopic, splitting into 6-10 often unequal rays with acute tips; expanded sporocarp 5.0-9.0 cm, the tips usually lying flat, gradually becoming elevated below the spore sac; alternatively in dry weather the developing rays may become incurved and fixed permanently around the spore sac; mycelial layer encrusted with debris; pseudoparenchymatous or fleshy layer up to 4.0 mm thick, buff, pale-tan, light-gray to medium-gray, frequently areolate, sloughing away to reveal a fibrous layer, streaked or mottled ochre to dark-brown over a tan background; in senescent material, rays weathering nearly white, sometimes conspicuously ribbed, and tinged greenish from algae; spore sac 1.8-2.5 cm broad, subglobose to compressed, with or without a short pedicel and apophysis; surface of spore sac initially dusted with minute granules, soon glabrous, grey to grayish-brown; peristome slightly elevated, with an inconspicuous lighter border, the opening round to slit-shaped, fringed with stiff dark-brown hairs; gleba dark-brown.
Spores 4.5-5.5 µm excluding ornamentation, nearly round, coarsely warted;
Scattered to gregarious under conifers; fairly common under Monterey cypress (Cupressus macrocarpa); fruiting from after the fall rains to late winter, occasionally during the summer months in coastal locations from fog drip.
Several other Geastrum species are of the same general form, and confident identification may require microscopic study (and a lot of expertise).
Geastrum coronatum Taxonomy and Etymology
The Crowned Earthstar was described scientifically in 1801 by Christiaan Hendrick Persoon, who gave it the binomial scientific name Geastrum coronatum by which is still generally known today.
Geastrum, the generic name, comes from Geo- meaning earth, and -astrum meaning a star.
The specific epithet coronatum means crowned.
Photo 1 - Author: yury_rebriev (Attribution-NonCommercial 4.0 International)
Photo 2 - Author: christian_ap (Attribution-NonCommercial 4.0 International)
Photo 3 - Author: helmling (Attribution-NonCommercial 4.0 International)
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