Snow Fungus

Snow Fungus is among the most delicate-looking fungi in the world: a cluster of thin, wavy, translucent white lobes that seem almost to be made of glass or melting ice. Individual fruiting bodies are typically 3–8 cm across and consist of many branching, leaf-like folds arising from a common base wedged in a crack in dead wood.

The genus Tremella is unusual in that its members are mycoparasites — fungi that parasitise other fungi. T. fuciformis grows on the mycelium of wood-decaying ascomycetes in the genera Annulohypoxylon and Hypoxylon, so its fruiting bodies often appear beside or on top of the black, crusty stromata of the host.

It is essentially a warm-climate species, common in the subtropics and tropics of Asia, the Pacific, Africa and the Americas, and it is one of the easiest jelly fungi to name in the field thanks to its pure white colour and frilly, seaweed-like structure.

Fruiting body

A gelatinous rosette 2–10 cm across and 1–5 cm high, made up of numerous thin, wavy, branching lobes that fold and interleave like a bunch of soft petals or a piece of marine algae. There is no cap, stipe, gills or pores — the whole structure is fertile over its surface.

Colour and texture

Pure white to translucent, nearly colourless when fully hydrated, sometimes with a faint yellowish or pinkish tone at the base or in older material. The texture is soft, slippery and elastic, considerably more yielding than the rubbery flesh of Auricularia. Lobes are usually under 1 mm thick and light passes readily through them.

Drying and spore print

On drying, the fruiting body shrinks into a hard, brittle, yellowish to orange-buff crust closely pressed to the wood, and re-expands to its full frilly form within hours of rewetting. The spore print is white. The base is often anchored in a bark crack where the host fungus is present.

Snow Fungus fruits on dead hardwood — fallen branches, small logs and dead attached limbs of broadleaf trees — typically in humid, shaded forest. It is closely tied to wood already colonised by Annulohypoxylon or Hypoxylon, whose black, hard, crust-like stromata are often visible on the same branch.

It is widespread in tropical and subtropical regions of Asia, Oceania, Africa, Central and South America and the warmer parts of North America, extending into warm-temperate zones. Fruiting occurs during wet seasons, chiefly summer to autumn in seasonal climates and after any prolonged rain in the humid tropics.

Rather than decaying wood directly, Tremella fuciformis is a mycoparasite: its hyphae penetrate and draw nutrients from the mycelium of the wood-rotting ascomycete host, forming specialised interaction cells where the two fungi meet. The wood decay itself is carried out by the host, so Snow Fungus is a second-order participant in the breakdown of dead branches.

Spores are produced across the surfaces of the gelatinous lobes and released into the air; germinating spores can also bud yeast-like cells, a life-cycle feature typical of Tremella. Because the jelly can dry and rehydrate repeatedly, one fruiting body may release spores across several separate rain events.

Tremella mesenterica has the same brain-like, folded jelly structure but is bright golden-yellow to orange. Phaeotremella frondosa and its relatives are brown and larger-lobed. Ductifera pululahuana is also white but forms small, blobby to cushion-shaped gelatinous masses rather than thin frilly lobes.

Exidia nucleata is whitish and translucent but forms lumpy cushions containing small hard white granules, and Sebacina species form crust-like or coral-like whitish masses that are firmer and less translucent. Among white jelly fungi, the thin, ruffled, seaweed-like lobes and association with black Annulohypoxylon crusts on hardwood identify Snow Fungus.