| Geastrum triplex | |
|---|---|
| |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Basidiomycota |
| Class: | Agaricomycetes |
| Order: | Geastrales |
| Family: | Geastraceae |
| Genus: | Geastrum |
| Species: | G. triplex
|
| Binomial name | |
| Geastrum triplex | |
| Synonyms | |
|
Geastrum indicum (Klotzsch) Rauschert | |
Geastrum triplex | |
|---|---|
 | Glebal hymenium |
 | No distinct cap |
 | Hymenium attachment is not applicable |
| Lacks a stipe |
 | Spore print is brown |
 | Ecology is saprotrophic |
 | Edibility is inedible |
Geastrum triplex is a fungus found in the detritus and leaf litter of hardwood forests around the world. It is commonly known as the collared earthstar, the saucered earthstar, or the triple earthstar—and less commonly by the alternative species name Geastrum indicum. It is the largest member of the genus Geastrum (or earthstar fungi) and expanded mature specimens can reach a tip-to-tip length of up to 12 centimeters (4+3⁄4 in).
Immature fruit bodies are spherical—somewhat resembling puffballs with pointed beaks—and are partially or completely buried in the ground. As the fungus matures, the outer layer of tissue (the exoperidium) splits into four to eight pointed segments that spread outwards and downwards, lifting and exposing the spherical inner spore sac. The spore sac contains the gleba, a mass of spores and fertile mycelial tissue that when young is white and firm, but ages to become brown and powdery. Often, a layer of the exoperidium splits around the perimeter of the spore sac so that it appears to rest in a collar or saucer. Atop the spore sac is a small pointed beak, the peristome, which has a small hole from which spores may be released.
The species is widespread and can be found in Asia, Australasia, Europe, and both North and South America. The fungus has a history of use in the traditional medicines of native North America and China. Fruit bodies have been analyzed chemically to determine their lipid content, and various chemical derivatives of the fungal sterol ergosterol have been identified.