Geastraceae

Geastraceae is a family of fungi in the Basidiomycota, order Geastrales. The family name derives from the genus Geastrum, the earthstars, and is characterized by fruiting bodies that exhibit a stellate or star-shaped exoperidium when mature. The inner spore-bearing structure, the endoperidium, forms a spherical or ovoid sac containing brown to dark spores. The outer layer splits into several rigid rays that stand away from the central mass, exposing the sac.

Most species are saprotrophic, growing on soil rich in organic material, leaf litter, or wood debris. They are found in a variety of habitats, with a worldwide, though often scattered, distribution, particularly in temperate regions. Reproduction occurs via basidiospores produced in the basidia of the endoperidium, released through a small apical pore when conditions are favorable.

The family contains several genera, the best known being Geastrum (earthstars). Other genera have been associated with the group in traditional classifications. Identification in the field relies on macroscopic features such as the number and arrangement of rays, the surface texture and color, and the morphology of the spore sac, often complemented by microscopic characters.

Ecology and human interactions: generally inconspicuous, not considered edible; some species have been used in traditional medicine or folklore, but there is limited scientific evidence for medicinal effects. Conservation status varies by species and region.