Red Pinwheel Marasmius

Marasmius pulcherripes is one of the small pinwheel parachutes of eastern North America and East Asia, a group of litter fungi whose caps are pleated like tiny umbrellas and whose stems are as fine as a hair. Its epithet refers to the beautiful stem, which is polished and dark and holds the coloured cap clear of the leaves.

Colour is the quickest guide to the species: pink, rose, coral or reddish purple caps that pale toward the margin, standing out against brown litter. As with all Marasmius, the flesh is tough rather than fragile and revives after dry spells.

It is a common summer species in moist woodland but easily overlooked because of its size, generally noticed only when a group of caps catches the light.

Cap

The cap is 3-12 mm across, bell-shaped to convex with a small central nipple or dimple, dry, and marked with deep radial grooves. It is rose-pink to reddish purple or coral, often fading to pinkish buff at the margin and with age.

Gills

Gills are whitish to pale pinkish, widely spaced and few in number, narrowly attached to the stem rather than joined to a collar.

Stipe

The stem is 3-6 cm long and hair-thin, wiry, smooth and shining, pale only at the very top and otherwise dark reddish brown to black, inserted directly into a needle or leaf without a mycelial pad at the base.

Flesh and spore print

The flesh is thin, tough and pliant, and the spore print is white with narrow, elongated spores.

This pinwheel fruits on fallen conifer needles, hardwood leaves, small twigs and other fine litter in moist woodland, frequently in mixed stands of pine, hemlock and oak. It is scattered rather than clustered and often appears in some numbers after summer thunderstorms.

It is widespread in eastern North America from early summer into early autumn, with comparable populations recorded in East Asia.

The species is a saprotroph of leaf and needle litter, its mycelium colonising individual leaves and needles and decomposing their cellulose. Colonised litter often shows bleached patches where the fungus is active.

Marcescence lets it fruit opportunistically: a flush that dries out during a hot spell will rehydrate and continue shedding spores when the next rain arrives, an efficient strategy for a fungus that occupies the most exposed layer of the forest floor.

Marasmius siccus, the Orange Pinwheel, is the same size and structure but rusty orange rather than pink. Marasmius haematocephalus is deeper wine-purple and is a tropical species. Marasmius fulvoferrugineus is larger and tawny brown.

Marasmius rotula is separated at once by its whitish cap and by gills that attach to a raised collar encircling the stem. Small pink Mycena species are similar in colour but have smoother, only finely lined caps, brittle flesh, and stems that are pale or grey rather than polished black.