(Astraeus smithii)
Conservation • Description • Habitat • Ecology • Distribution • Taxonomy
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Description |
Until recently, this species was known as Hygroscopic Earthstar (Astraeus hygrometricus). Almost every North American field guide includes this mushroom under that name. Studies since 2003 found several new species that were previously included in A. hygrometricus. The type species A. hygrometricus occurs only in southern France and Turkey. Three species occur in North America. Only one, A. smithii, occurs in Minnesota. Smith’s Earthstar is a late season, small or medium-sized mushroom—small when closed, medium-sized when open. It is similar in appearance to true earthstars in the genus Geastrum, but it is not even closely related. It is an example of convergent evolution, where species of different lineages evolve similar features. It appears on the ground in late summer and fall, singly, scattered, or in groups. It is found in sandy soil in forest edges, old fields, pastures, roadsides, and other disturbed sites. It has a mutually beneficial relationship (mycorrhizal) with the tiny rootlets of trees and shrubs, absorbing sugars and amino acids while helping the tree absorb water. The fruiting body begins as a round to flattened case below the soil surface. It emerges as it expands and looks like a puffball. As it matures the outer layer of the case splits into 6 to 15 pointed rays, exposing a nearly spherical spore sac. When fully expanded, the fruiting body is ⅜″ to 3″ or more in diameter. The rays are tough and leathery when moist, about 1 ⁄32″ (1 mm) thick, and more or less triangular. The upper (inner) surface is dark brown to black and is broken up into somewhat polygonal pieces. When fresh, it sometimes has a pale tan foreground with dark cracks and crevices, appearing like dried, cracked mud in a dry lake bed. The lower (outer) surface is covered with matted, blackish, hair-like fibers. When moist, the rays arch backward to the ground, raising the spore sac, and facilitating distribution of the dust-like spores. In dry conditions the rays fold back over the spore sac and become hard. Old specimens have blackish-brown rays. The spore sac is stalkless, grayish or brownish, thin, papery, ⅜″ to 1¼″ in diameter, and more of less spherical or somewhat flattened. The outer surface is roughened by numerous particles. There is a poorly-defined opening (pore) at the top. The interior (spore mass) when young is white, solid, and divided into oval-shaped compartments. As it matures it becomes brown to cocoa-brown, and powdery. At maturity, the spore case ruptures through the pore at the top, and the spores are disbursed by the wind. It is not edible due to the toughness of the rays. Similar mushrooms collected and eaten in Asia, once thought the same, have subsequently been identified as new species. |
Similar Species |
Habitat and Hosts |
Disturbed sites; old fields, pastures, roadsides |
Ecology |
Season |
Late summer and fall |
Distribution |
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Sources All historic records and sightings of Astraeus hygrometricus in Minnesota should be considered to be of Astraeus smithii, the only former Astraeus hygrometricus found in the state. The map at left includes records and sightings of both Astraeus smithii and Astraeus hygrometricus. |
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6/23/2024 | ||
Occurrence |
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Widespread in North and Central America. Common in the Great Lakes and coastal states. Less common in Minnesota. |
Taxonomy |
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Kingdom |
Fungi (fungi) |
Subkingdom |
Dikarya |
Division |
Basidiomycota (club fungi) |
Subdivision |
Agaricomycotina (jelly fungi, yeasts, and mushrooms) |
Class |
Agaricomycetes (mushrooms, bracket fungi, puffballs, and allies) |
Subclass |
Agaricomycetidae |
Order |
Boletales (boletes and allies) |
Suborder |
Sclerodermatineae |
Family |
Diplocystidiaceae |
Genus |
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Family Species Molecular and phylogenetic studies since 2003 have identified several new species that were previously classified as A. hygrometricus. The most recent of these studies (Phosri et al., 2013) showed that the type species, A. hygrometricus, occurs only in southern France and Turkey. In the United States, western specimens were grouped under A. pteridis. Two new species were described, A. morganii in southern U.S. and Mexico, and A. smithii in central and northern U.S. According to Michael Kuo (MushroomExpert.com), the 2013 paper “…is riddled with errors, inconsistent species descriptions, and poor documentation; I believe further research is required before accepting the paper's suggestions.” |
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Subordinate Taxa |
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Synonyms |
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Astraeus hygrometricus Geastrum hygrometricum |
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Common Names |
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Barometer Earthstar False Earthstar Hygroscopic Earthstar Water-measure Earthstar |
Glossary
Mycorrhizal
A symbiotic, usually beneficial relationship between a fungus and the tiny rootlets of a plant, usually a tree.
Visitor Photos |
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Luciearl |
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… They were growing in very sandy soil. It is filling in with voluntary Jack Pines since the blowdown 2015. |
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Found several groups on the roots of uprooted trees. |
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Earthstar Mushroom They don't last long. Happen to catch this one on the right day. Went back a few days later and it was shrinking. |
Tiffany Snyder |
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MinnesotaSeasons.com Photos |
Slideshows |
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Visitor Videos |
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Other Videos |
Astraeus hygrometricus.wmv |
About
Published on Jan 30, 2010 |
Astraeus hygrometricus rehydrating over about 40 minutes |
About
Published on Sep 27, 2015 The "water measurer" earth star, although not a true earth star fungus, absorbs water from the air, opening its petals in response, and so is said to measure the relative humidity. Here, one is placed in a shallow pool of water and allowed to re-hydrate, with photos taken at 10 second intervals over about 40 minutes. |
Time Lapse of the Barometer Earthstar, Astraeus hygrometricus (Pers.) Morgan |
About
Published on Sep 17, 2013 Time lapse footage at 2 seconds of a Barometer Earthstar. This specimen was brought in to the Trailside Nature Museum by Harry Zirlin. Read more on Tom Volk's website: http://botit.botany.wisc.edu/toms_fungi/dec2003.html |
False earth star (Astraeus smithii) |
About
Published on Mar 19, 2013 I believe this is a false earth star (Astraeus smithii). Collingswood, March, under oak. |
Visitor Sightings |
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This button not working for you? |
Luciearl |
Location: Fairview Twp. |
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Tiffany Snyder |
Location: Frederick MI |
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Luciearl 10/1/2023 |
Location: Fairview Twp … They were growing in very sandy soil. It is filling in with voluntary Jack Pines since the blowdown 2015. |
Luciearl 9/27/2023 |
Location: Fairview Twp, Cass County |
P Jaegs 8/21/2022 |
Location: Carlton County, MN, near Nickerson all over, around the cabin and driveway. |
Luciearl 3/26/2021 |
Location: Fairview Twp., Cass County Found several groups on the roots of uprooted trees. |
Luciearl 9/27/2020 |
Location: Cass County |
Luciearl 7/19/2018 |
Location: Cass County They don't last long. Happen to catch this one on the right day. Went back a few days later and it was shrinking. |
MinnesotaSeasons.com Sightings |
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Created: 7/25/2018 Last Updated: © MinnesotaSeasons.com. All rights reserved. |