Astraeus hygrometricus Sclerodermataceae Barometer Earthstar

Picture 1 Click here (after the page is fully loaded) to see it opening

Asterias hygrometrica 39kb

Astraeus hygrometricus, Barometer Earthstar. Many specimens of this unusual and rare fungus were found under Beech and Oak trees in a cemetery. At first we thought they were Beech nut cases trodden into the soil, as they are half buried. When dry, the outer skin is closed over the inner, so that it resembles an old-fashioned leather button, but when wetted it opens out in rays to expose the inner sac, which eventually splits at the apex to release the spores. See the action replay by clicking above. This is of a very old specimen, and shows the opening over a two hour period. You will need to enable Javascript to see the action. In appearance it is reminiscent of an Earthstar, Geastrum sp. but is not closely related, one difference being in spore size.

Click on the photo for a larger image

La Société Guernesiaise Guernsey Biological Records Centre Botany Section Species list Previous Species Next Species