Rosy Earthstar

The Rosy Earthstar is a big, fleshy species whose colour gives it away while fresh. As the outer wall splits and the rays fold back, their exposed inner surface takes on a warm pinkish to reddish or flesh-coloured flush, deepening where handled or bruised, before fading to a dull brown as the fruit body dries. Few other earthstars show this tint.

Structurally it is a plain member of the genus: a sessile spore sac with no stalk, seated in a broad star of five to eight thick rays, topped by a conical, silky-fibrillose mouth that is neither grooved nor sharply outlined by a court. Its size — expanded specimens can reach 10 cm across — and its substantial, almost rubbery ray tissue add to the impression of a heavyweight earthstar.

It is a woodland fungus of deep humus under both broadleaves and conifers, appearing in autumn and often persisting as a weathered brown star into winter.

Star and rays

Expanded fruit bodies are 4–10 cm across, among the largest earthstars. The outer peridium splits into 5–8 broad, thick, fleshy rays that recurve and may arch under the fruit body. When fresh the inner ray surface is pinkish, flesh-coloured or reddish, especially where damaged, fading to buff and then brown with age and cracking into a coarse mosaic as it dries.

Spore sac

The sac is 1.5–3 cm across, globose to slightly flattened, pale buff to greyish-tan, smooth or finely mealy, and is sessile — resting directly on the star with no stalk, no collar and no apophysis.

Peristome

The mouth is conical and fibrillose, made of fine converging silky fibres, without grooves and without a sharply delimited pale court around it. In some specimens the fibres are slightly paler than the sac but the boundary remains indistinct.

Interior

The young unopened fruit body is onion-shaped, buried in litter and covered in soil-bound mycelial felt. Inside, the gleba ripens from firm and white to a fine brown spore powder around a central columella.

The Rosy Earthstar grows in deep humus and leaf litter in both broadleaf and coniferous woodland, and is also found in plantations, on mossy woodland banks, in shrubberies and occasionally on dune scrub. It prefers well-drained ground with a thick fermenting litter layer and is often found in small scattered troops.

Fruiting is mainly autumn, though weathered stars persist through winter. The species is widespread across Europe, North America and temperate Asia, and is recorded rather sparsely elsewhere; it is generally a lowland to lower-montane fungus.

Geastrum rufescens is saprotrophic, decomposing woodland litter, humus and fine buried root and wood debris. The size of its fruit bodies implies a substantial and well-established mycelium in the soil, and colonies often reappear in the same patch of woodland floor year after year.

Spore dispersal uses the standard earthstar bellows: raindrops or passing animals compress the thin papery sac and expel a puff of brown spores through the fibrous mouth. The broad recurved rays lift and steady the sac above the litter, keeping the mouth exposed to air movement.

The Collared Earthstar (Geastrum triplex) is the most similar in size, but its thick inner fleshy layer characteristically cracks and separates to leave a raised collar or bowl around the base of the sac, and it lacks the pinkish flush. The Rounded Earthstar (Geastrum saccatum) is smaller and has its fibrillose mouth enclosed in a sharply delimited circular court.

The Fringed Earthstar (Geastrum fimbriatum) is smaller, paler and thinner-rayed, with no pink tones. Stalked species — the Crowned Earthstar (Geastrum coronatum), Beaked Earthstar (Geastrum pectinatum) and Striated Earthstar (Geastrum striatum) — are ruled out at once by the presence of a stalk and, in the last two, a grooved beak.