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Geastrum triplex.jpg
Geastrum triplex
Geastrum saccatum.jpg
Geastrum saccatum
Scientific classification
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Subclass: Phallomycetidae
Order: Geastrales
Family: Geastraceae
Genus: Geastrum
Type species
Geastrum pectinatum

About 50; See text

Geastrum (orthographical variant Geaster)[1] is a genus of mushroom in the family Geastraceae. Many species are known commonly as earthstars.

The name comes from geo meaning earth and aster meaning star.

The name refers to the behavior of the outer peridium. At maturity, the outer layer of the fruiting body splits into segments which turn outward creating a star-like pattern on the ground. The inner peridium is a spore sack. In some species, the outer peridium splits from a middle layer, causing the spore sack to arch off the ground. If the outer peridium opens when wet and closes when dry, it is described as hygroscopic.

In some species, the inner peridium is borne on a stalk or pedicel. The columella is a column-like clump of sterile tissue to be found inside the inner peridium. The network of fertile tissue inside the inner peridium, the capillitium, arises from the columella. The mouth in most species of "earth-stars" is quite prominent, often arising as a small cone at the apex of the inner peridium. It may be even or sulcate (grooved).[2]


There are roughly 50 species in the genus Geastrum.[3] Some similar species that are otherwise difficult to differentiate using classical morphological features (such as G. triplex, G. saccatum, and G. lageniforme) can be identified using chemical spot tests that detect phenoloxidase enzymatic activity, as well as differences in the crystal structure of calcium oxalate deposits.[4] Species include:


  1. ^ Demoulin V. (1984). "Typification of Geastrum Pers.: Pers. and its orthographic variant Geaster (Gasteromycetes)". Taxon 33 (3): 498–501. doi:10.2307/1220990. 
  2. ^ Johnson MM. (1928). "The Gasteromycetae of Ohio". Ohio Biological Survey Bulletin 22 4 (7): 271–352. 
  3. ^ Kirk PM, Cannon PF, Minter DW, Stalpers JA. (2008). Dictionary of the Fungi (10th ed.). Wallingford, UK: CAB International. p. 274. ISBN 978-0-85199-826-8. 
  4. ^ Zamora JC, Calonge FD, Martín MP. (2013). "New sources of taxonomic information for earthstars (Geastrum, Geastraceae, Basidiomycota): phenoloxidases and rhizomorph crystals". Phytotaxa 132 (1): 1–20. doi:10.11646/phytotaxa.132.1.1. 
  5. ^ a b da Silva BDB, Cabral TS, Marinho P, Ishikawa NK, Baseia IG. (2013). "Two new species of Geastrum (Geastraceae, Basidiomycota) found in Brazil". Nova Hedwigia 96 (3–4): 445–56. doi:10.1127/0029-5035/2013/0089. 
  6. ^ Fazolino EP, Calonge FD, Baseia IG. (2008). "Geastrum entomophilum, a new earthstar with an unusual spore dispersal strategy". Mycotaxon 104: 449–53. 
  7. ^ Domínguez De Toledo, Laura S. (1996). "Geastrum lilloi sp. nov. from Argentina". Mycologia 88 (5): 858–62. JSTOR 3760982. 
  8. ^ Kasuya T, Hosaka K, Uno K, Kakishima M. (2012). "Phylogenetic placement of Geastrum melanocephalum and polyphyly of Geastrum triplex". Mycoscience. doi:10.1007/s10267-012-0186-z. 
  9. ^ Douanla-Meli C, Langer E, Calonge FD. (2005). "Geastrum pleosporus sp nov., a new species of Geastraceae identified by morphological and molecular phylogenetic data". Mycological Progress 4 (3): 239–50. doi:10.1007/s11557-006-0127-3.