Geastrum

Geastrum (orthographical variant Geaster) is a genus of puffball-like mushrooms in the family Geastraceae. Many species are commonly known as earthstars.
The name, which comes from geo meaning earth and meaning star, 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 called a spore sac. In some species, the outer peridium splits from a middle layer, causing the spore sac 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 found inside the inner peridium. The network of fertile tissue inside the inner peridium, the capillitium, arises from the columella. This is where basidia and basidiospores are produced. 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).
They are generally not toxic but considered non-edible due to their fibrous texture in the mature stage at which they are generally found.
Species
Although the Dictionary of the Fungi (2008) estimated roughly 50 species in Geastrum, a more recent estimate (2014) suggests that there may be up to 120 species. Geastrum coronatum Pers. has been proposed as the conserved type for the genus. 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, a
differences in the crystal structure of calcium oxalate deposits or DNA sequences. Species include:
Geastrum aculeatum
Geastrum albonigrum
Geastrum andrewsii
Geastrum argentatum
Geastrum argentinum
Geastrum australe
Geastrum austrominimum
Geastrum benitoi
Geastrum britannicum
Geastrum berkeleyi
Geastrum bushnellii
Geastrum campestre
Geastrum clelandii
Geastrum congolense
Geastrum corollinum
Geastrum coronatum
Geastrum dissimile
Geastrum drummondii
Geastrum dubowskii
Geastrum echinulatum
Geastrum elegans
Geastrum elliptice
Geastrum entomophilum
Geastrum episcopale
Geastrum fimbriatum
Geastrum flexuosum
Geastrum floriforme
Geastrum fornicatum
Geastrum fuscogleba
Geastrum hieronymi
Geastrum hirsutum
Geastrum huneckii
Geastrum hungaricum
Geastrum inpaense – Brazil
Geastrum kotlabae
Geastrum kuharii
Geastrum lageniforme
Geastrum leptospermum
Geastrum lilloi
Geastrum litchiforme
Geastrum lloydianum
Geastrum magnosporum
Geastrum melanocephalum
Geastrum meridionale
Geastrum minimum
Geastrum mirabile
Geastrum morganii
Geastrum ovalisporum
Geastrum oxylobum
Geastrum papinuttii
Geastrum parvisporum
Geastrum parvistriatum
Geastrum pectinatum
Geastrum pleosporus
Geastrum pouzarii
Geastrum pseudolimbatum
Geastrum quadrifidum
Geastrum reticulatum
Geastrum rhizophorum
Geastrum rufescens
Geastrum rugulosum
Geastrum rusticum – Brazil
Geastrum saccatum
Geastrum schmidelii
Geastrum schweinitzii
Geastrum senoretiae
Geastrum setiferum
Geastrum smardae
Geastrum smithii
Geastrum stiptatum
Geastrum striatum
Geastrum subiculosum
Geastrum tichifer
Geastrum triplex
Geastrum velutinum
Geastrum verrucoramulosum
Geastrum welwitschii
Geastrum xerophilum
Geastrum xylogenum
References
Sources
New Zealand Species
British Species
Czech Species and Photos
Ponce de Leon, Patricio, A Revision of the Family Geastraceae, Field Museum of Natural History 1968
Agaricomycetes genera