Myriostoma

Myriostoma is a fungal genus in the family Geastraceae. The genus is monotypic, containing the single species Myriostoma coliforme. It is an earthstar, so named because the spore-bearing sac's outer wall splits open into the shape of a star. The inedible fungus has a cosmopolitan distribution, and has been found in Africa, Asia, North and South America, and Europe, where it grows in humus-rich forests or in woodlands, especially on well-drained and sandy soils. A somewhat rare fungus, it appears on the Red Lists of 12 European countries, and in 2004 it was one of 33 species proposed for protection under the Bern Convention by the European Council for Conservation of Fungi. The fruit body, initially shaped like a puffball, is encased within an outer covering that splits open from the top to form rays. These rays curve down to expose an inner papery spore case, which contains the fertile spore-bearing tissue, the gleba. The fungus is unique among the earthstars in having a spore case that is supported by multiple stalks, and is perforated by several small holes suggestive of its common names salt-shaker earthstar and pepperpot. It is the largest of the earthstar fungi, and reaches diameters of up to 12 cm (4.7 in). Its spherical spores have elongated warts that create a ridge-like pattern on their surface. The spores are dispersed when falling water hits the outer wall of the spore sac, creating puffs of air that force the spores through the holes. The species was first mentioned in the scientific literature by Samuel Doody in the second edition of John Ray's Synopsis methodica stirpium Britannicarum in 1696. Doody briefly described the mushroom like so: 'fungus pulverulentus, coli instar perforatus, cum volva stellata' (a powdery mushroom, perforated like a colander, with a star-shaped volva), and went on to explain that he found it in 1695 in Kent. It was first described scientifically as a new species in 1776 from collections made in England by James Dickson, who named it Lycoperdon coliforme. He found it growing in roadside banks and hedgerows among nettles in Suffolk and Norfolk. Nicaise Auguste Desvaux first defined and published the new genus Myriostoma in 1809, with the species renamed Myriostoma anglicum (an illegitimate renaming). Christian Hendrik Persoon had previously placed the species in Geastrum in 1801, while Samuel Frederick Gray would in 1821 describe the genus Polystoma for it. Myriostoma coliforme received its current and final name when August Carl Joseph Corda moved Dickson's name to Myriostoma in 1842, replacing Desvaux's name. In North America the fungus began to be reported in the late 19th century, first from Colorado by Charles Horton Peck, and later from Florida, collected by Lucien Underwood in 1891; both findings were reported by Andrew Price Morgan in April 1892. In 1897, Melville Thurston Cook also reported having collected it the year before from 'Albino Beach'. Curtis Gates Lloyd described Bovistoides simplex from a South African specimen in 1919, but in 1942, William Henry Long examined that specimen and concluded that it was a weathered spore sac of M. coliforme that had become detached from the outer star-shaped exoperidium. This conclusion was confirmed in a later study of the material. Myriostoma had been classified in the family Geastraceae until 1973, when British mycologist Donald Dring placed it in the Astraeaceae based on the presence of trabeculae (stout columns that extend from the peridium to the central core of the fruit body) in the gleba, and the absence of a true hymenium. In his 1989 monograph, Stellan Sunhede returned it to the Geastraceae. Molecular analysis of DNA sequences has confirmed the traditional belief that Myriostoma and Geastrum are closely related. Czech naturalist and mycologist Václav Jan Staněk proposed a variety capillisporum in 1958, which has been sunk back into synonymy with the species. M. coliforme is the sole species in Myriostoma, making the genus monotypic. Because the original type material has been lost, in 1989 Sunhede suggested that Dickson's illustration in his 1776 publication (tab. III: 4a & b) be used as the lectotype. The specific epithet is derived from the Latin words colum, meaning 'strainer', and forma, meaning 'shape'—Berkeley's vernacular name 'Cullenden puff-ball' also refers to a colander. Gray called it the 'sievelike pill-box'. The generic name is from the Greek words μυρίος, meaning 'countless' and στόμα, meaning 'mouth' (the source of the technical term stoma). The species is commonly known as the 'salt-and-pepper shaker earthstar' or simply the 'pepperpot'.