Beaked Earthstar Identification Guide

The Setting

Earthstars reward slow walking with your eyes on the ground. This one turns up in conifer woodland and in gardens, churchyards and shelterbelts planted with spruce, pine, cypress or yew — anywhere a deep, dry, undisturbed bed of needle litter has built up under evergreens. It also appears on nutrient-rich, sheltered banks and among the humus at the base of old hedges.

The first impression is of a small star of leathery rays, 3 to 6 centimetres across when open, with a grey-brown ball held up in the middle. Fresh specimens sit clear of the litter, often with the rays bent strongly downward and backward so that the whole fruiting body is levered up on their tips. Because the rays are tough and the sac is durable, weathered specimens survive for months, and a good proportion of the ones you find will be last season's, bleached and stripped but still showing the diagnostic features.

Getting the Fruiting Body Out Cleanly

Lift a specimen with the litter around it rather than pulling it. The base often has needles and soil cemented to the underside of the rays and, importantly, a distinct rooting attachment where the fruiting body was anchored. Brushing the underside carefully with a soft brush is worth doing, because part of the identification is what the base of the sac looks like, and that is hidden under debris in most field finds.

The Rays

There are usually five to nine rays, formed as the tough outer wall splits from the apex downward. They are firm and leathery, tan to greyish-brown or dull ochre on the inner face, frequently cracking with age into a fine mosaic. In fresh material they arch and recurve strongly; in dry weather they may fold partly inward, though this species is not strongly and repeatedly hygroscopic in the way the barometer earthstars are.

The rays are typically not fornicate — that is, they do not lift the whole fruiting body up on a separate cup of mycelium-bound soil the way a few relatives do — but they do frequently curl right under, which produces a similar arching effect and confuses beginners.

The Spore Sac, Stalk and Collar

This is where the identification is actually made, and it needs a hand lens.

Look at the junction between sac and rays. In this species the spore sac is raised on a short but distinct stalk, a pedicel a few millimetres tall. Where that stalk meets the underside of the sac, there is a swollen collar-like structure — the apophysis — which sits like a shallow saucer or rounded shoulder at the base of the sac. Below and around the pedicel there are often several fine longitudinal ridges or a faint radiating pattern running down onto the ray surface.

The sac itself is 1 to 2 centimetres across, roughly spherical to slightly ovoid, and grey to grey-brown, often with a faint whitish frosting or pruina that rubs off on the fingers, leaving darker patches.

The Beak

Now the character the species is named for. At the apex of the sac is a well-defined mouth raised into a distinct conical or narrowly pointed beak, clearly delimited from the rest of the sac and often set on a paler zone. The critical detail is that this beak is finely and regularly grooved — plicate — with numerous narrow furrows running from tip to base like the folds in a closed umbrella or the flutes on a column.

A hand lens shows this immediately on fresh material. On weathered specimens, look at the beak in raking light and the fluting still reads. A ragged, torn or fibrous-fringed opening, or a smooth unfurrowed cone, means you are looking at a different species.

Interior and Section

Cut a mature specimen vertically. Inside the sac is a dry, loose, cocoa- to umber-brown powder of spores mixed with a mesh of fine, tough threads called capillitium. Rising from the base into the powder is a slender sterile column, the columella, which reaches partway up the cavity — worth noting, since its presence and shape are used across the genus.

Immature specimens, which are hard to find because they develop mostly buried, are firm and white to marbled inside, darkening from the centre outward as spores mature.

Dispersal Rather Than a Spore Print

Do not attempt a spore print. Spores are produced inside a closed sac and leave through the beak. When a raindrop or a falling needle strikes the elastic sac wall, the chamber compresses and puffs a small cloud of spores out through the fluted mouth; the raised stalk lifts the sac clear of the litter so the cloud catches moving air. Press a dry sac gently with a fingertip and you can watch the mechanism work.

If you want to see the spores, tap dust onto a slide. They are globose and covered in coarse warts, typically 4 to 6 micrometres across, and the ornamentation is used in fine separations within the genus.

Substrate, Season and Ecology

The Beaked Earthstar is a saprotroph. It decomposes needle litter, buried woody fragments and humus, taking nothing from living roots, and it favours dry, sheltered, undisturbed accumulations of that material: mature conifer plantations, spruce and pine shelterbelts, yew and cypress in churchyards and old gardens, hedge banks and the deep litter under garden conifers.

Fruiting is chiefly late summer through autumn, but because the fruiting bodies are so persistent, records span the whole year. Populations are typically small and localised; a productive patch of litter will often produce a handful of fruiting bodies year after year in the same square metre.

Separating It From Other Earthstars

Geastrum striatum. The most demanding comparison. It also has a stalked sac with an apophysis and a grooved beak, but the collar is a sharply defined, flattened, disc-like apophysis with a distinct rim, and the sac is often smaller with a bluer-grey tone. This species shows a more rounded shoulder-like apophysis and usually longer, finer grooving on the beak.

Geastrum quadrifidum. Usually four rays, fornicate — the rays arch down onto a persistent cup of soil-bound mycelium that stays behind on the ground — and the beak is fibrous or finely fringed rather than regularly grooved.

Geastrum fornicatum. Larger and strongly arched on a mycelial cup, with a felted, unfurrowed mouth zone.

Geastrum triplex. The commonest large earthstar of broadleaf litter; the thick fleshy inner ray layer cracks to leave a conspicuous collar around a sessile sac, and the mouth is a fibrous cone with no grooves and no stalk.

Geastrum rufescens and Geastrum saccatum. Sessile sacs with fibrous, unfluted mouths.

Barometer earthstar (Astraeus). Thick cracked leathery rays that repeatedly open and close with humidity, a sessile sac with no stalk and no collar, and a ragged apical tear instead of a defined beak. It is also mycorrhizal, unlike the saprotrophic true earthstars.

Field Checklist

Conifer or garden litter; five to nine leathery recurving rays; spore sac raised on a short stalk; rounded collar-like apophysis at the sac base; grey-brown sac with a rubbable bloom; sharply defined conical beak with fine regular grooves; brown powder and a columella inside; persistent year-round.