Collared earthstar (Geastrum triplex)

The star of the show in broadleaf woodland. This charming fungus would look at home at the bottom of the sea. It may be small but its transformation from bulb-shape to star, to saucer, to support its delicate spore sac is truly remarkable.

This star-shaped fungus is usually found among leaf litter in deciduous woodland.

Credit: Laurie Campbell / WTML

It is the most common earthstar species in the UK.

Credit: Arco Images Gmbh / Alamy Stock Photo

Quick facts

Common names: collared earthstar, triple earthstar, saucered earthstar

Scientific name: Geastrum triplex

Family: Geastraceae

Fruiting season: after rain in late summer to autumn but can be seen all year round

Habitat: among leaf litter in deciduous woods, especially with beech on chalky soils. Sometimes found under coniferous trees, especially on sloping ground

What does collared earthstar look like?

Initially resembling a small brown bulb, after it splits open into pointed rays, the collared earthstar is star-shaped. As the rays continue to turn back on themselves, they create the ‘saucer’ which the round fruiting body sits on.

Cap: it can measure up to 10cm across. At first it looks like a small brown bulb and is partially or completely buried in the ground. Then the outer skin splits and peels back into 4–8 pointed rays, covered in a fleshy layer. The layer cracks as the rays bend back and curl under – a process which raises up the spore bag (similar to a small puff ball) – leaving it sitting on the saucer-like base. The spores escape through a peristome – a small, fringed opening, at the top of the spore bag.

Gills/spores: the spore sack measures up to 5cm in diameter and up to 10cm when fully outstretched. The spore mass is dark brown and the spores are round and covered in small, spiny warts. They disperse when raindrops fall on the delicate skin of the spore bag.

Not to be confused with: Geastrum saccatum and several other Geastrum species, though they tend to be smaller than the collared earthstar.

Credit: imageBROKER / Alamy Stock Photo

Where to find collared earthstar

It is fairly common in England and is also found in Wales, Northern Ireland and central Scotland, particularly in East Lothian. You’re most likely to see one in woods with deciduous, hardwood trees, especially those with lots of leaf litter. They like woods with beech on chalky soils in the south. They can be found under coniferous trees or even on sand dunes, in scrub and along roadside hedgerows, especially on sloping ground.

Spores disperse when raindrops fall on its spore bag.

Credit: Nature Photographers Ltd / Alamy Stock Photo

Did you know?

There are 64 species of fungi in the Geastraceae family across the world, but only a handful in the UK.

Mythology and symbolism

The Native American Blackfoot Confederacy called collared earthstars ka-ka-toos – meaning 'fallen stars' – and believed them to be indicators of supernatural events.

Credit: FLPA / Alamy Stock Photo

Uses of collared earthstar

Even though they’re not poisonous, they don’t taste good. However, they were used in the traditional medicines in Chinese and Native American cultures.

Did you know?

Its generic name ‘Geastrum’ originates from 'Geo' which means earth, and ‘astrum' which means a star; while ‘triplex’ refers to the three layers than make up the fungus.

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