Amber Jelly Roll

This spring, I’m exploring some of PEI’s early-fruiting fungi, and today’s example sounds more like a pastry than a mushroom. Meet Amber Jelly Roll (Exidia crenata).

Photo: Amber Jelly Roll (Exidia crenata) on PEI.

As you might guess, this is one of the Jelly Fungi. I’ve highlighted a few fall-fruiting members of this group before (including Cat’s-Tongue and Orange Jelly-spot), and you can find them in the Fungus Profiles section this blog.

Although they’re grouped together in guidebooks because of their similar growth form, Jelly Fungi are not all closely related. As biologist Terrence Delaney of the University of Vermont notes, some Jelly Fungi are less closely related to each other than we are to Hummingbirds!

While Amber Jelly Roll may not share much DNA with some of the other Jellies, it does share a common feature: pliable cell walls. This allows Jelly Fungi to expand in wet conditions and contract when it’s dry. That useful adaptation that means they don’t need to build an entire fruiting body from scratch when conditions are right to spread their spores – they can just plump up. It also allows them to take advantage of warmer, wet periods in winter and early spring when many other fungi are dormant, and is one reason it’s common to see Amber Jelly Roll this time of year.

Most mushrooms make a living in one of three ways. Some form relationships with plants (mycorrhizal), others steal nutrients from plants or fungi (parasitic), and many feed on decaying organic matter (saprotrophic). Amber Jelly Roll is saprotrophic, one of the brown-rot fungi that feeds on wood’s cellulose (a carbohydrate) leaving behind decay-resistant lignin that lasts for centuries.

Residue from brown-rot fungi doesn’t play a major role in nutrient cycling but it is very important to soil’s structure and moisture-holding ability, as well as to carbon storage. We often recognize the value of deadwood and the ecosystem services it provides, ignoring the critical roles fungi play in governing the rate at which deadwood decomposes, provides those services, and releases its carbon to the atmosphere.

Amber Jelly Roll is common in eastern North America, though most of our Island records come from Queens and Kings Counties. It has pliable, brown to purplish fruiting bodies with concave depressions between ridges, and grows on dead or dying hardwood branches and twigs. This is one of our many edible fungi, though I haven’t yet found enough to bother harvesting it.

There are other species that look a bit like Amber Jelly Roll, but many are also edible. For example, Black Witches’ Butter (Exidia glandulosa) is darker-coloured, flatter on the wood and more blob-like than Amber Jelly Roll. Wood Ear (Auricularia americana) can be similar in colour to Amber Jelly Roll but is usually more ear-shaped – sometimes eerily so! – and considered a choice edible by some foragers. Leafy Brain (Tremella foliacea) is often lighter in colour and tends to be squishy rather than jelly-like, while Pine Jelly (Exidia saccharina) grows on conifers rather than hardwoods. It’s useful to remember that not all Jelly Fungi are considered edible, and positive identification of any fungus or plant is essential before eating it.

With fungi, plants, and animals all doing their spring things across the Island, it’s a great time to appreciate PEI Untamed!