Geastrum triplex - Collared Earthstar

Taxonomy

Phylum: Basidiomycota

Class: Agaricomycetes

Order: Geastrales

Look in woodland for this member of the (hopelessly jumbled, taxonomically, but useful from an identification point of view) gastromycetes group of fungi.

Collared Earthstars are most often found under hardwood trees, but we have also found them in coniferous woodland. If you cut through a young fruitbody the interior is white, but it gradually turns into a dark brown powdery mass as the spores mature.

Spores are emitted from the apical hole as breezes blow across it, and much larger puffs of spores escape when raindrops hit and compress the spore-sac.

Identification Guide

Description	Collared Earthstars are larger than other earthstar species, and they have a spore-sac diameter up to 5cm and arms that span twice that distance when fully outstretched. A flattened spherical spore-sac holds the powdery gleba with which the spores are distributed. A hole on the top of the sac releases spores when the wind blows across it or raindrops impinge upon it. The opening on the top of the spore-sac is pointed at first, and is surrounded by a fuzzy ring slightly paler fawn-brown than the rest of the spore-sac outer surface. As with other earthstars, the bulb is mounted on a star-shaped base, but Geastrum triplex is commonly referred to as the 'collared earthstar' because in many instances the arms crack as they bend, with the result that the spore-sac seems to be sitting on a separate saucer-like layer.
Dimensions	The bulb is typically 2 to 5cm across and roughly spherical, and fully outstretched the rays are up to 10cm across.
Other features	When fully expanded the rays of the earthstar more than double its diameter. The number of star rays is very variable - those illustrated here have six or seven rays but some found nearby had only five rays.
Stem	None.
Spores	Dark brown.
Odour/taste	Not noticeable.
Habitat	Found under hardwood and coniferous trees, often on sloping rather than flat ground
Season	Fruiting after rain in late summer and autumn; visible all year round .
Occurrence	Fairly frequent in beechwoods in southern Britain but found throughout the UK and in Ireland. This species occurs throughout Europe and is also common in the USA.
Similar species	Several other Geastrum species are of the same general form, although generally smaller, and confident identification requires a lot of expertise.