Geastrum floriforme

Description

Geastrum floriforme is a flattened sphere mushroom that holds the powdery gleba with which the spores are distributed. A hole on the top of the 'bulb' releases spores when the wind blows across it. The bulb is mounted on a star-shaped base that looks rather like the petals of a daisy, and that closes tighter when dry. The bulb is typically 10 to 20 mm across and roughly spherical. The number of star rays is very variable. Several other Geastrum species are of the same general form, and confident identification requires a lot of expertise.

This is a common species in central and southern mainland Europe and it occurs also in some parts of North America.

An important field mark of Geastrum floriforme is its hygroscopic habit, i.e. the ability of the rays to expand and close around the spore sac with changing humidity. This contrasts with most Geastrums, which at maturity do not respond to changes in humidity and are "fixed."s

Common names: Daisy Earthstar.

Mushroom Identification

1. Sporocarp

   Fruiting body subglobose, 10-20 mm broad before splitting, outer mycelial layer initially binding debris, soon lost, thus appearing debris free; expanded fruiting body 1.5-3.5 (4.0) cm broad; exoperidium splitting to form 5-10 rays, upper surface of rays various shades of brown, more or less glabrous, strongly hygroscopic, i.e. curled over the spore sac in dry weather, lying flat to slightly revolute when moist; endoperidial body or spore sac sessile, 6-15 mm, the surface gray-brown in youth, furfuraceous, fading to nearly white in senescent specimens; peristome indistinct i.e. usually the same color as the spore sac, the opening slightly elevated with a fibrillose margin.

2. Spores

   Spores globose, warted, 5.5-7.0 µm including ornamentation, with a single guttule.

3. Spore Mass

   Dark brown.

4. Habitat

   Solitary to scattered in dry, open areas and sandy soils; distribution poorly known; collected in coastal areas, but may occur in montane regions; fruiting after fall rains, present throughout the year in dried state; uncommon, easily overlooked.

History

This mushroom was described scientifically in 1842 by Italian mycologist Carlo Vittadini (1800 - 1865), who gave it the binomial scientific name Geastrum floriforme by which it is still generally known today.

Synonyms of Geastrum floriforme include Geastrum delicatus Morgan, Geastrum simulans Lloyd, Geastrum spegazzinianum De Toni, Geaster floriformis Vittad., and Geastrum sibiricum Pilát.

Geastrum, the generic name, comes from Geo- meaning earth, and -astrum meaning a star. Earthstar it is, then. The specific epithet floriforme means shaped like a flower (and to be more precise a daisy flower!).

Photo sources:

Photo 1 - Author: Lukas from London, England (CC BY-SA 2.0)

Photo 2 - Author: Jacob Kalichman (Pulk) (CC BY-SA 3.0)

Photo 3 - Author: Lukas from London, England (CC BY-SA 2.0)

Photo 4 - Author: Nathan Wilson (nathan) (CC BY-SA 3.0)