Red Edge Brittlestem

Red Edge Brittlestem, Psathyrella corrugis (long known as Psathyrella gracilis), is among the most elegant members of the Psathyrellaceae. Everything about it is slender: a small conical cap, a wiry stem several times the cap's width in length, and paper-thin flesh that collapses quickly once mature.

Its distinguishing feature is the gill edge. In fresh, well-developed specimens the sterile edge cells carry a pink, rose or reddish tint that contrasts against the increasingly blackish gill faces — the character behind both the English and several older scientific names.

The species is common and widespread but easily missed, since the thin stem and small cap disappear among grass and leaf litter. Careful examination of the gill edge with a lens, together with the rooting stem base and blackish spore print, generally confirms it.

Cap

1-3 cm across, conical to bell-shaped, expanding only slightly and often keeping a pointed or umbonate centre. The margin is finely grooved or wrinkled when moist and frequently splits with age. Hygrophanous: date-brown, greyish brown or reddish-tan when wet, drying to pale ochre, greyish-buff or almost cream from the centre outward.

Gills

Adnate to narrowly adnexed, moderately spaced, broad. Pale greyish at first, then dull brown and finally blackish as spores ripen, with the edge distinctly flushed pink to rose-red in fresh material — best seen with a hand lens on the underside of a young cap.

Stipe

6-12 cm long but only 1-2.5 mm thick, thread-like, straight, hollow and very brittle, white to pale cream with a silky sheen and often a few fine fibrils near the top. The base is characteristically drawn out into a slender rooting extension buried in the substrate. No ring.

Flesh and spore print

Flesh extremely thin and fragile, watery brown to white, with no marked smell. Spore print blackish with a purple-brown cast.

The species grows on soil, in leaf litter and among grass, typically where buried twigs, wood chips, dead roots or compost-rich material lie beneath the surface. Woodland floors, path edges, hedgerows, gardens, mulched beds, parks and grassy clearings all suit it, on both broadleaved and conifer sites.

It is common and widespread throughout temperate Europe, North America and parts of Asia. Fruiting typically runs from late summer through autumn, often continuing into the first mild frosts, and it appears singly, in small scattered groups or in loose troops rather than in fused clusters.

Psathyrella corrugis is a saprotroph on buried plant remains. Its mycelium ramifies through leaf litter, wood chips and small woody fragments in the upper soil, decaying cellulose and lignin and helping incorporate coarse debris into humus. The long rooting stem base is a mycelial cord connecting the fruiting body to that buried substrate.

Fruiting bodies are short-lived, appearing after rain, maturing rapidly and shrivelling within days. The species colonises disturbed and mulched ground readily, which is why it is such a frequent find in gardens and along managed woodland paths as well as in natural woodland.

Psathyrella multipedata shares the thin stem but grows in dense bouquets fused at a common base and lacks a coloured gill edge. Psathyrella prona is similarly slender and can also show a faint reddish gill edge, but has a smaller, more greyish cap and a shorter stem, and typically grows in short grass.

Parasola plicatilis has a comparably wiry stem but its cap is deeply pleated like a tiny parasol with widely spaced grey gills that do not deliquesce into a mass. Psathyrella candolleana is altogether larger and paler with a veil-fringed cap margin and no red gill edge.