Overview
The Pepper-pot Earthstar (Myriostoma coliforme), also affectionately known as the salt-shaker fungus, is a morphologically unique and globally rare gasteroid fungus belonging to the family Geastraceae. While typical earthstars feature a single central stalk and a lone apical pore, Myriostoma is the only fungal species on Earth that produces a spore-bearing sac supported by multiple columnar stalks and perforated with numerous apical ostioles, creating an uncanny resemblance to an antique pewter pepper caster.
Biology and Physical Characteristics
The fruiting body develops underground as a subterranean globose ball before erupting through the turf during autumn rains. As it matures, the thick outer layer (exoperidium) splits into seven to twelve pointed, recurved rays that fold backward to elevate the entire central spore body off the damp ground. The inner spore sac (endoperidium) is supported by a ring of several distinct, slender columnar pedicels (stalks) rather than a single stem. Most remarkably, the upper surface of the papery, silver-grey spore sac is punctured by five to thirty discrete, circular ostiole pores lined with delicate fringe-like margins.
Behavior and Ecology
As a saprotrophic decomposer, Myriostoma coliforme plays an important role in breaking down recalcitrant lignin and cellulose in well-drained, sandy soils beneath thermophilous deciduous trees like oaks, elms, and robinias. Spore dispersal is powered by physical kinetic impacts: when raindrops or passing mammals strike the flexible, taut endoperidial membrane, air pressure inside the sac forces puffs of dark brown, warted basidiospores upward through all the perforated ostioles simultaneously like fine chimney smoke.
Conservation and Human Impact
Assessed as Endangered or Vulnerable across European Red Lists and legally safeguarded under national biodiversity action plans, Myriostoma coliforme has suffered dramatic historical declines. In the United Kingdom, it was declared extinct for over a century before being rediscovered at a single sandy hedge bank in Norfolk in 2006. The primary drivers of its decline are agricultural eutrophication, nitrogen deposition, modern hedgerow removal, and the abandonment of traditional woodland grazing.
Interesting Factoid
Myriostoma coliforme is the only fungus known in the world that possesses multiple stem stalks and multiple spore-dispersion holes, functioning like a hydraulic multi-nozzle pepper shaker whenever struck by raindrops.
Last updated: October 2026