Orange Mosscap

Orange Mosscap is one of the smallest mushrooms most people notice, standing only a few centimetres high but glowing against green moss like scattered pinheads. It is common in short mossy turf, on shaded lawns, on woodland banks, and anywhere a moss carpet stays damp.

Rickenella is a small genus of moss-associated fungi with an omphalinoid shape: a cap that is depressed or navel-like at the centre with gills running conspicuously down the stem. Despite the tiny size, the structure is well defined and easy to see with a hand lens.

What makes the genus biologically interesting is its relationship with mosses. Rather than simply decomposing dead plant material, these fungi grow intimately among moss rhizoids and stems, and the fruit bodies are almost always found where a suitable moss carpet exists.

Cap

Minute, typically 0.3-1.5 cm across, convex with a distinct central depression from the outset that deepens into a small navel. The surface is smooth, slightly translucent when wet, bright orange to yellow-orange at the centre and fading to pale yellow or cream at the striate margin.

Gills

Deeply decurrent, running well down the stem, distant and fairly broad, white to very pale cream and contrasting strongly with the orange cap.

Stipe

Extremely slender, 2-5 cm tall but often less than 1 mm thick, cylindrical, orange-yellow above and paler below, minutely downy under a lens, flexible and slightly tough for its size. There is no ring and the base simply disappears into the moss.

Flesh & spore print

The flesh is insubstantial and pale. The spore print is white. Under the microscope the species has conspicuous projecting cystidia on cap, gills, and stem, which cause the fine downy appearance.

Look for it in cushions and carpets of moss: on lawns and mown grassland, in damp woodland glades, on shaded earth banks, roadside verges, dune slacks, and on mossy rotting wood. It rarely occurs where moss is absent, and colonies often follow the outline of the moss patch.

The season is long, running from spring through late autumn wherever moisture persists, with the best showings in cool damp weather. It is widespread and abundant throughout temperate and boreal Europe, Asia, and North America.

Rickenella fibula lives in close association with mosses, with its hyphae growing among and into the rhizoids and basal stems of the moss carpet. This relationship is best described as biotrophic rather than simply saprotrophic, and it explains the fungus's dependence on living moss rather than on plain soil or litter.

Because moss carpets are stable and long-lived, populations persist in the same patch for years and fruit repeatedly through the season. The tiny fruit bodies are short-lived individually, but new ones appear continuously in damp weather, so a mossy lawn may show scattered orange caps for months.

Rickenella swartzii is the same size and shape but has a darker brownish or violet-tinged disc at the centre of the cap and a distinctly violet apex to the stem. Xeromphalina campanella has similar orange colouring and decurrent veined gills but is tougher, grows in dense swarms on conifer logs, and has a dark wiry stem with a tuft of tawny hairs at the base.

Loreleia species are orange and moss-loving too but are associated with liverworts rather than mosses and often have a more strongly funnel-shaped cap. Small orange Mycena and Galerina species differ in having adnexed or narrowly attached gills rather than gills running far down the stem, and Galerina leaves a rusty rather than white spore deposit.