Beech Jellydisc

Beech Jellydisc (Neobulgaria pura) is a gelatinous ascomycete in the Helotiales that behaves like a jelly fungus but is in fact a cup fungus with a rubbery, water-swollen structure. Fruit bodies begin as small translucent knobs and expand into shallow top-shaped discs, often so crowded that they compress one another into irregular polygons.

The colour is delicate: pale pinkish-buff, flesh pink or faintly lilac, semi-translucent when wet and duller when drying. Colonies can cover long stretches of a fallen beech trunk, forming a pale, glistening crust of individual discs.

It is one of the most characteristic autumn fungi of mature beech woodland and a reliable indicator that a fallen beech branch has retained its bark.

Fruiting body

Individual discs 0.5–2 cm across, top-shaped or turbinate, narrowed to a short broad base and expanding above into a flat or slightly convex fertile surface. Growing in dense crowded clusters, they become angular and lobed through mutual pressure.

Surfaces

The upper fertile surface is smooth, pale pinkish-buff to flesh-coloured, sometimes with a lilac or violet tinge, and semi-translucent when moist. The lower and outer surfaces are similar in colour but finely roughened.

Flesh and spore print

The flesh is gelatinous and rubbery-elastic throughout, quivering when the log is knocked, and shrinking markedly in dry weather. The spore print is white; spores are smooth and elliptical.

Neobulgaria pura fruits on fallen and dead standing beech in particular, favouring branches and trunks that still carry their bark, and appearing on the bark surface or on exposed wood. It is occasionally recorded on other broadleaved trees but beech is by far the usual host.

The season is autumn, sometimes lingering into early winter in mild spells. It is widespread in the beech forests of Europe and occurs in temperate broadleaf woodland elsewhere in the northern hemisphere.

The fungus is a saprophyte that decays the outer wood and inner bark of recently fallen beech, forming part of the early to mid succession of decomposers on large woody debris. The gelatinous consistency is an adaptation to fluctuating moisture — the discs shrivel to inconspicuous specks in dry weather and swell again after rain, resuming spore release.

Colonies persist for several weeks and often occupy the same log across successive seasons until the wood is broken down.

Ascocoryne sarcoides, the purple jellydisc, is a deeper reddish-purple to violet and often takes contorted, brain-like or club-shaped forms rather than tidy discs. Ascocoryne cylichnium is likewise purple and more distinctly cup-shaped. Bulgaria inquinans is much tougher, dark brown to black with a shiny black disc, and grows on oak. Basidiomycete jellies such as Exidia species are lobed, brain-like or button-like and lack the neat flat fertile disc of Neobulgaria.

Pale pinkish-buff colouring, crowded top-shaped discs and a beech substrate together identify Beech Jellydisc.