California Fungi: Geastrum fornicatum

Sporocarp

Fruiting body round to globose, 1.5-2.5 cm broad, the outer layer typically with embedded dirt and debris; at maturity splitting into 4-6 rays which recurve and elevate the spore sac, the tips remaining attached to a basal cup; expanded fruiting body up to 6 cm broad, and 8 cm tall; rays dark-brown, the surface scaling irregularly in age to expose a light brown under layer; spore sac 1.5-2.5 cm in diameter, rounded to slightly flattened, on a short stalk, dark brown, with a roughened surface, opening via an apical tear or slit.

References

Arora, D. (1986). Mushrooms Demystified. Ten Speed Press: Berkeley, CA. 959 p.
Calonge, Francisco D. (1998). Flora Mycologica Iberica. Vol. 3. Gasteromycetes, I. Lycoperdales, Nidulariales, Phallales, Sclerodermatales, Tulostomatales. J. Cramer: Berlin, Germany. 271 p.
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Ellis, M.B. & Ellis, J.P. (1990). Fungi without Gills (Hymenomycetes and Gasteromycetes). Chapman and Hall: London, England. 329 p.
Moreno, G., Lizárraga, M., Esqueda, M. & Coronado, M.L. (2010). Contribution to the study of gasteroid and secotioid fungi of Chihuahua, Mexico. Mycotaxon 112(1): 291-315.
Pegler, D. N., Læssøe, T. & Spooner, B. M. (1995). British Puffballs, Earthstars, and Stinkhorns. Royal Botanic Gardens: Kew, England. 255 p.
Siegel, N. & Schwarz, C. (2016). Mushrooms of the Redwood Coast. Ten Speed Press: Berkeley, CA. 601 p.
Sunhede, Stellan (1989). Geastraceae (Basidiomycota) -- Morphology, Ecology, and Systematics with Special Emphasis on Northern European Species. Fungiflora: Oslo, Norway. 535 p.