Geastrum saccatum

Geastrum saccatum Fr., 1829 (Syn: Geastrum lloydianum Rick, 1906; Geastrum saccatum var. cinereum V. J. Staněk, 1958; Geastrum saccatum var. lloydianum (Rick) Rick, 1961; Geastrum saccatum f. parvulum Boiffard, 1998; Geastrum saccatum var. parvulum Speg., 1926; Geastrum saccatum f. saccatum Fr., 1829; Geastrum saccatum var. saccatum Fr., 1829; Geastrum saccatum var. walkeri Coker, 1927; Geastrum saccatum var. wichanskyi V. J. Staněk, 1958);      

rounded earthstar; 

 

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Geastrum saccatum, commonly known as the rounded earthstar,^[1] is a species of mushroom belonging in the Geastrum genus. It is found in North America and Europe and is found growing on rotting wood. It is considered inedible by mushroomers, because of its bitter taste. It is a common mushroom, but collections are at their peak during late summer.  

The opening of the outer layer of the fruiting body in the characteristic star shape is thought to be due to a buildup of calcium oxalate crystals immediately prior to dehiscence.  

G. saccatum is distinguished from other earthstars by the distinct circular ridge or depression surrounding the central pore. In Brazil, its common name translates to “star of the land”.^[2]  

The immature fruiting body is 0.6 to 2.5 centimetres (0.24 to 0.98 in) in diameter and 0.8 to 1.5 centimetres (0.31 to 0.59 in) tall. Initially, the fruiting body is egg-shaped – similar in appearance to puffballs – and has strands of mycelia (rhizomorphs) at the base that attach it to the growing surface. The ‘skin’, or peridium, is composed of two separate layers: the outer layer (exoperidium), which is a golden tan to yellowish brown color, separates away from the inner basidiocarp, and splits into several rays that curve backward (recurve) to the base. The mushroom is 2 to 5 centimetres (0.79 to 2.0 in) in diameter after the rays have expanded. Unlike some other members of the genus Geastrum (such as Geastrum fornicatum) the arms do not push the basidiocarp off the ground; rather, it lies flat. The inner spore-bearing basidiocarp is 0.5 to 2 centimetres (0.20 to 0.79 in) broad, and has a central pore surrounded by a circular dull-brown apical disc; the disc is distinctly ridged or depressed.^[1] The inside of the interior sphere is white when young, but matures into a mass of brown, powdery spores mixed with thick-walled fibres known as capillitium.^[3] 

The spores are rounded, with warts, and have dimensions of 3.5–4.5 µm.^[3] 

G. saccatum is saprobic, and grows scattered or clustered together in leaf litter of humus, usually in late summer and fall. It has a cosmopolitan distribution, and is well adapted to tropical regions.^[2] It is common in Hawaiian dry forests.^[4] The species has been collected in the United States, Argentina, Brazil, Canada, China, Congo, Cuba, Mexico, Panama, South Africa, West Africa, Tanzania, and Tobago.^[5] 

A study has shown that the formation of calcium oxalate crystals on the hyphae that form the endoperidial layer of the basidiocarp is responsible for the characteristic opening (dehiscence) of the outer peridial layers.^[6] Calcium oxalate is a common compound found in many fungi,^[7] including the earthstars.^[8] Curtis Gates Lloyd was the first to note the presence of these crystals on the endoperidium of Geaster calceus (now known as Geastrum minimum).^[9] The formation of calcium oxalate crystals stretches the layers of the outer walls, pushing the inner and outer layers of the peridium apart.^[6] 

The related species Geastrum fimbriatum does not have an apical disc, and its pores are slightly smaller. G. saccatum may be distinguished from G. indicum by the absence of loose tissue forming a collar around the base of the endoperidium. 

(From Wikipedia on 2.8.13)

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request for id (mixed thread): Attachments (1).  5 posts by 4 authors.

Can you pls help me in identifying species of these fungi. They were photographed in Deer Park, Hauz Khas, New Delhi in July/ August 2008.
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Third is Geastrum. Pls identify species.
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These are ….., Geastrum saccatum and ….. respectively beyond any doubt.

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Thanks for the confirmation.

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Geastrum saccatum AT MAR 2017/24 : 2 posts by 2 authors. Attachments (1)

Geastrum saccatum
Earthstar
Shimla
August 2016

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References:

Catalogue of Life  Wikipedia  Mushroom Expert  India Biodiversity Portal