Leafy Brain

Description

The Leafy Brain is a gelatinous fungus with a brown, brain-like folded fruiting body that with age forms lobes resembling seaweed or leaves. The fruiting body is usually 3–15 cm, cinnamon-brown to dark brown, springy and slippery after rain. In dry weather it shrinks, hardens and turns black, and softens again when moistened.

It grows on dead branches and wood of conifers, where it parasitises the mycelium of the bleeding conifer parchment. Fruiting bodies can be found all year round, most often in autumn and in mild winters. In Poland it is rare.

It can be told from the ear fungi by the lack of an ear shape, and from similar jelly fungi by growing on conifers; species from broadleaved trees (e.g. Phaeotremella frondosa) are usually paler and larger. It is tasteless and not suitable for eating.

Identification features

Cap

No typical cap; the fruiting body is tremelloid (gelatinous), 3–15 cm across (descriptions give different ranges; some up to 5 cm), exceptionally very large. In young specimens it is folded like a brain, later lobed, with irregular, fused lobes and folds with rounded edges, resembling seaweed. Colour ranges from cinnamon-brown with a flesh-coloured tinge to brown and dark brown.

Hymenophore (underside of the cap)

No gills, tubes or spines. The hymenium covers the entire surface of the fruiting body, and the spore-bearing basidia form over its whole surface.

Stem

No stem; the fruiting body is attached directly to the substrate.

Flesh

Gelatinous and springy when wet; in dry weather hard, cartilaginous and almost black, regaining its shape when moistened. Taste very mild, odour insignificant; the flesh consists mainly of water. The flesh should not be tasted for identification.

Spore print and spores

Spore print white. Spores roundish to broadly ellipsoid or ellipsoid, smooth, 5.5–12 × 4.5–9 µm (descriptions give different ranges). They germinate by a hypha or by yeast-like cells.

Habitat and distribution

Ecology. A parasite of the mycelium of the bleeding conifer parchment (Stereum sanguinolentum) growing in dead conifer wood; it attacks the hyphae in the wood, not the host's fruiting bodies. Fruiting bodies appear on dead, still attached or freshly fallen conifer branches.

Distribution. Widespread in the temperate zone of the Northern Hemisphere: Europe, northern Asia, North America; some descriptions also give South America, Africa and New Zealand. After the separation of several similar species, the distribution data need updating. Rare in Poland; on the Red List of fungi in the category of undetermined threat status (I). Not legally protected in Poland.

Fruiting. Fruiting bodies may appear all year round, most often in autumn and during mild winters, provided it is not too dry.

What can it be confused with?

• Phaeotremella frondosa — Parasitises parchment fungi (Stereum) growing on broadleaved trees; fruiting bodies usually larger and paler.
• Phaeotremella fimbriata — A European species parasitising Stereum rugosum on broadleaved trees; fruiting bodies smaller, dark brown to black.
• Auricularia auricula-judae (Jew's ear) — Ear-shaped fruiting body, growing most often on elder and other broadleaved trees.
• Auricularia mesenterica (tripe fungus) — Grows on broadleaved wood; the upper side of the fruiting body is zoned in several colours, the underside veined.
• Exidia saccharina (caramel jelly fungus) — Gelatinous fruiting body growing only on conifers, without a distinctly lobed, leaf-like structure.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• The epithet foliacea means “leafy” and refers to the lobed shape of the fruiting body; in English the fungus is called “leafy brain”.
• Persoon described the species in 1800; DNA studies later showed that it is not closely related to the type species of the genus Tremella, and it was moved to the genus Phaeotremella.
• The yeast stage of this fungus was described in 1962 as a separate species, Cryptococcus skinneri, found in the droppings of a bark beetle feeding on balsam fir; only DNA sequencing showed that it is the same organism.
• The Polish name “trzęśnik listkowaty” was only given in 2025, to match the genus name Phaeotremella.