''Geastrum minimum '' or tiny earthstar is an inedible species of

mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is ...

belonging to the genus ''

Geastrum ''Geastrum'' (orthographical variant ''Geaster'') is a genus of puffball-like mushrooms in the family Geastraceae. Many species are known commonly as earthstars. The name, which comes from ''geo'' meaning ''earth'' and meaning ''star'', refers ...

''. Although rare, it is widespread in Europe, where it occurs in a range of habitats. It is a priority species in the UK, where it has been found in the

sand dunes A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...

Holkham National Nature Reserve Holkham National Nature Reserve is England's largest national nature reserve (NNR). It is on the Norfolk coast between Burnham Overy Staithe and Blakeney, and is managed by Natural England with the cooperation of the Holkham Estate. Its comp ...

. The species was first described by

Lewis David de Schweinitz Lewis David de Schweinitz (13 February 1780 – 8 February 1834) was a German-American botanist and mycologist. He is considered by some the "Father of North American Mycology", but also made significant contributions to botany. Education B ...

in 1822.

Description

Fruit bodies The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life c ...

are initially roughly spherical before the outer

peridium The peridium is the protective layer that encloses a mass of spores in fungi. This outer covering is a distinctive feature of gasteroid fungi. Description Depending on the species, the peridium may vary from being paper-thin to thick and rubbe ...

splits to form a star with 6–11 "rays". When opened, the diameter of the fruit body is . The inner spore sac is spherical or egg-shaped, and measures . The more-or-less round

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

s measure 5–5.5–4–4.5

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Uni ...

and have warts on their surface.

References

minimum In mathematical analysis, the maxima and minima (the respective plurals of maximum and minimum) of a function, known collectively as extrema (the plural of extremum), are the largest and smallest value of the function, either within a given r ...

Fungi described in 1822 Fungi of Europe Inedible fungi Taxa named by Lewis David de Schweinitz {{Geastrales-stub