Geastrum sp. (genus) (An earthstar)

The species of Geastrum are known colloquially as earthstars. Each mature fruitbody consists of a puffball-like spore sac atop a star-like base. Some species are easy to identify visually, others are not.

Before you started looking at microscopic details, some of the questions you'd ask when trying to identify a Geastrum are:   

• Does the spore sac sit directly on the base or is it held up by a stem (and if so, what is its size)?
• Are the arms of the base hygroscopic (in other words, do they fold inwards in dry conditions and open out in moist conditions)?
• Does soil/debris adhere tightly to the undersides of the basal arms or are they free of soil/debris (or at least where any soil/debris is easily removed by light brushing)?
• What is the nature of the apical mouth, through which the spores puff out? Two examples are a (1) conical, strongly pleated mouth (as shown here: http://www.cpbr.gov.au/fungi/images-captions/geastrum-sp-ostiole-0144.html) and (2) a fibrillose mouth (http://www.cpbr.gov.au/fungi/images-captions/geastrum-sp-ostiole-0143.html).  

 You'd also note colour, texture and size.

Regional distribution

Geastrum sp. (genus) is listed in the following regions: