Striated Earthstar

The Striated Earthstar carries two distinctive structures at once. Its grey spore sac ends above in a narrow beak finely scored with radiating grooves, and below it sits on a short stalk from which a broad, flaring collar — a well-developed apophysis — spreads out like a skirt. No other common Geastrum shows both features together, so a mature specimen is straightforward to name.

The surrounding star is formed of five to nine narrow rays that recurve and often arch enough to tilt the fruit body up on their tips. Ray inner surfaces are pale buff to brown, drying darker and cracking, and the outer surfaces are felted with soil and litter.

Unlike the conifer specialists in the genus, this species is a fungus of nutrient-rich, nitrogen-enriched ground — hedge bottoms, nettle beds, shrubbery mulch and disturbed garden soil — where its stiff, weather-hardy fruit bodies can be found long after autumn.

Star and rays

Expanded fruit bodies span 2–6 cm. The outer peridium splits into 5–9 pointed rays that bend well back, sometimes arching so that the star rests on its tips. Inner ray surfaces are pale buff to brown and typically crack into a mosaic as they age; outer surfaces are felted and encrusted with soil.

Collar and stalk

Beneath the spore sac is a short stalk, usually 2–4 mm, topped by a pronounced flaring apophysis that spreads outward as a distinct collar or skirt encircling the base of the sac. Viewed from the side this collar is the single most useful character.

Spore sac and beak

The sac is 0.8–2 cm across, globose to ovoid, grey to bluish-grey or grey-brown, smooth to slightly mealy, often with a faint pale bloom. It tapers above into a sharply defined conical beak marked with fine longitudinal grooves converging on the mouth.

Interior

The gleba changes from white and firm in the immature buried stage to a fine dark brown spore powder around a slender columella. The sac wall is papery and elastic, so a light knock or a raindrop produces a visible puff from the beak.

The Striated Earthstar favours rich, nitrogen-enhanced soils: hedge bottoms, nettle beds, shrubberies, garden borders, mulched beds, farmyard margins, parkland and the edges of woodland tracks. It tolerates disturbed ground and is often found under dense herbaceous cover or among ivy.

Fruiting runs from autumn into winter, and the tough fruit bodies persist for months so records span much of the year. It is widespread but local in Europe and is also recorded from North America, Asia, Africa and Australasia, generally in lowland, warm and sheltered situations.

Geastrum striatum is saprotrophic, decaying leaf litter, herbaceous debris and humus in fertile topsoil. Its association with nettle beds and mulched ground reflects a tolerance for high-nitrogen substrates that many woodland earthstars avoid.

The fruit body develops below the litter as a felted ball, then expands and splits. The short stalk and collar hold the sac just clear of the ground while the grooved beak concentrates the spore stream, so each raindrop strike drives a directed puff of dark spores into the air above the litter.

The Beaked Earthstar (Geastrum pectinatum) is the main confusion, sharing a grooved beak, but it has a distinctly longer stalk, a merely swollen rather than flaring apophysis, and a finely granular or pruinose sac surface. The collar of G. striatum is broad and skirt-like and visible from the side.

The Crowned Earthstar (Geastrum coronatum) has a stalked dark sac but a silky, entirely ungrooved mouth. The Collared Earthstar (Geastrum triplex) also shows a bowl-like collar, but that structure is formed by the cracking of the thick fleshy inner layer of the star itself rather than by an apophysis, its sac is sessile, and its mouth is fibrillose rather than furrowed.