In 2005, Ann Hargrove, a member of NSBFG, found specimens of two extremely rare Earthstars at the National Trust Estate at Stourhead. These were two hygroscopic Geastrum species, G. campestre and G. floriforme. A report of these finds was published by Alick Henrici in Field Mycology 7 (2) 2006.

In May 2007, as part of the Tyntesfield Audit, John and Roy found a small Earthstar on dry ground above the Chapel. Thinking it was probably a small sample of the very common sessile earthstar G. fimbriatum, John agreed to “look at it”. Several weeks later, he found it at the back of the fridge! - in a very dried up state (above right). After placing it in a moist box for less than an hour, the Earthstar had almost completely recovered (above left). Clearly this was another hygroscopic Earthstar. But which one? As can be seen in the photographs, this Earthstar did not have a beak (peristome) and an examination of the spores showed many were 10 microns long - far too large to be a Geastrum. After consulting Field Mycology and a phone call to Alick Henrici, it was clear that this fungus was not a species of Geastrum, but was Astraeus hygrometricus - the Barometer Earthstar, which though less rare than the hygroscopic Geastrums, is on the Red Data List Ed 1. Thus Astraeus hygrometricus is not a real Earthstar in the genus Geastrum, but in fact is closely related to the Scleroderma Earthballs - a relationship supported by the rough appearance of the spore sac and lack of a peristome.

So, keep your eyes open for hygroscopic Earthstars. If you find one that does not have a peristome and has large spores, you have found The Barometer. If you do find some, please contact us at nsbfg6@hotmail.com.

See a video of it opening