Fungi Key – Earthstars

The Earthstars are members of the Lycoperdaceae, the puffballs, and are in the
genus Geastrum. They have a different structure to other fungi and are even
different from other puffballs, so people who study them use terms that you may be
unfamiliar with. A short glossary and some diagrams are provided below to help.

Glossary

Asperate – with a roughened surface
Endoperidium – the inner ‘ball’ that contains the spores
Exoperidium – the outer covering that contains the endoperidium and which splits to
form the stars or rays as the fungus matures
Glabrous – with a smooth surface
Hygroscopic – the rays close in dry weather, they become involute
Non-hygroscopic – the rays remain in a permanently expanded state
Pedicellate – with a stalk between the exoperidium and the ‘ball’
Peristome – a complex structure at the top of the ‘ball’ which can be:
- Sulcate – grooved
- Fibrillose – surrounded by thin fibres
Rays –the individual splits of the exoperidium; they can be:
- Involute – incurved partially enclosing the endoperidium like a lotus flower
- Revolute – recurved, bending downwards and lifting it off the ground
Rugose – wrinkled
Stoma – the pore at the top of the ball where the spores are released. It may be
simple (naked) or complex (peristome)
Tomentose – felted

Some Geastrums have changed their names. The latest species names are given in
the key; the older names (shown in brackets) are often on Herbarium specimen
labels.

Trial Key for Geastrum

1.	Stoma naked	2
1.	Stoma with peristome	3
2.	Exoperidium hygroscopic, acute rays involute	*G. floriforme*
2.	Exoperidium not hygroscopic, wide rugose rays, endoperidium pedicellate (G. fenestratum)	*G. fornicatum*
3.	Peristome sulcate	4
3.	Peristome fibrillose	7
4.	Exoperidium not hygroscopic, revolute, endoperidium pedicellate, spores 5.5 – 7.5 µm diameter (G. pectinatum)	*G. tenuipes*
4.	Exoperidium hygroscopic, involute	5
5.	Endoperidium sessile, involute (G. drummondii)	*G. ambiguum*
5.	Endoperidium pedicellate, thick and rugose on outside	6
6.	Endoperidium asperate, spores 6 – 8 µm diameter	*G. campestre*
6.	Endoperidium glabrous, spores 4 – 5.5 µm diameter	*G. clelandii*
7.	Stars small, < 30 mm diameter, endoperidium pedicellate	*G. austrominimum*
7.	Endoperidium sessile (pedicel absent), stars larger than 30 mm diameter	8
8.	Exoperidium tomentose (G. velutinum)	*G. javanicum*
8.	Exoperidium glabrous	9
9.	With a collar between the exoperidium and the endoperidium, spores 4 – 5 µm diameter	*G. triplex*
9.	Lacking a collar, spores either larger or smaller	10
10	Spores 2.5 – 3.5 µm diameter	*G. saccatum*
10.	Spores 7 – 8 µm diameter	*G. australe*

Note: G. triplex is the most common earthstar recorded in Queensland; G. saccatum
is also known from several collections; all the others appear to be rare, with only 1 to
3 collections. If you find an earthstar, photograph it, collect it, make careful notes
using this key and then deposit it at the Queensland Herbarium at Mt Coot-tha.

Gretchen Evans
25 April 2022
Version 1.3