The Kingdom Under the Woods

There’s another world beneath the trees that like many essential backroom functions is hidden and shrouded in mystery. It is the kingdom of the fungi, and the autumn is a great time to see them.

The power of a name

Mushrooms and toadstools are the fruiting spores of fungi and the distinction between them first appeared in print in the mid fifteenth century and reflects the dilemma about what is and isn’t safe to eat. So, while mushrooms were defined as edible, toadstools were defined as inedible or poisonous. Browse through any field guide, and you’ll quickly find this distinction isn’t accurate, but with over 15,000 species in the UK of which about 3,000 produce visible fruiting spores, it’s hardly surprising that this traditional definition isn’t watertight.

Gills and spore patterns are used to identify fruiting spores. Photo credit: Jane Halliday

An intricate interconnected web

Whether you’re looking at a short-lived clump or a solitary mushroom or toadstool, you’re only seeing the tip of the ‘iceberg.’ The much longer-lived body is underground. The body of the fungus is a mass of thread-like filaments called hyphae (singular hypha). Growing from the tip each hypha repeatedly branches, until it forms an interconnected wood-wide web. Invisible to the eye, the hyphae can be spotted when they fuse together to form the mycelium that can sometimes be seen at the base of trees or in the soil as white strands.

Sulphur Tuft. Photo credit: Tom Williams

Different survival strategies

It wasn’t until the microscope was invented that we discovered that unlike plants and animals, fungi don’t contain differentiated organs, and unlike plants they can’t photosynthesise. Instead, fungi eat by secreting enzymes, which break down and absorb the nutrients and minerals in organic matter, and because their cell walls contain chitin (also found in crab shells), they can penetrate tree roots and dead wood. This gives fungi different survival strategies: exchanging nutrients for sugars (mycorrhizal); taking nutrients from a living host (parasitic) or breaking down organic matter (saprobic).

Exchanging nutrients for sugars

As the name suggests the Beechwood Sickener which ranges from white to crimson is only found in beechwoods, and while its hot and bitter taste gives us upset stomachs, its presence is essential for healthy beech trees.  The connections between the hyphae and the tree roots, enables mycorrhizal fungi and groups of trees to circulate food in a mutually beneficial relationship. The fungi give the trees access to nutrients, such as phosphorous and nitrogen, from a much larger area than their roots could reach, whilst the fungi obtain sugars from the trees. Hallucinogenic Fly Agaric is often found with birch trees but also forms mycorrhizal relationships with pines and spruce. It’s  vivid red cap and white spots  is an iconic image but it’s appearance can change. The white spots are part of the veil that encased the young mushroom, and the Fly Agaric can lose them when they are washed off by the rain.

The iconic Fly Agaric mushroom. Photo credit (left): Jane Halliday, (right) Simon Smith

The parasitic approach

Like other lifeforms, fungi can be parasitic, taking all their food from a living host and causing heartwood rot.  The most visible parasitic fungi are the brackets, whose fruiting spores can be seen all year round, and which are also called polypore or shelf fungi.

The distinctive Turkey Tail fungus grows out from the tree in a series of multi-coloured concentric circles with a paler edge and is often found in tiered groups. Described as weakly parasitic , it can also live by decomposing dead deciduous trees.  Traditionally used in Chinese medicine to boost the immune system, it contains antioxidants and is being studied as a potential cancer support treatment.

The concentric rings of Turkey Tails are paler at the rim. Photo credit: Jane Halliday

The decomposers

Healthy woodlands always contain dead wood and leaf litter and because of the tough cellulose and lignin they contain, it takes a specialist group of saprobic fungi to break them down. King Alfred’s Cakes, also called cramp balls, and coal fungus, may look small, but the fungus is strong enough to break down the lignin in dead and decaying wood. They can remain on the wood for several years becoming harder and drier and were traditionally used as fire lighters.

Clouded Funnel (close up) and Clouded Funnel growing in a circular pattern on the woodland floor; King Alfred’s Cakes. Photo credit: Jane Halliday

About 3 tonnes of leaf litter fall onto every hectare of deciduous woodland each year, and the Clouded Funnel is one of the fungi that breaks them down and releases their nutrients back into the soil. In open areas where a fungus has an uninterrupted food supply it grows in a circular pattern and as the fruiting spores appear at the edge of the growth circle it creates a magical fairy ring. In Yarner, the roots break up these patterns and instead you can see the Clouded Funnel growing in arcs among the trees.

There’s still a lot to discover about fungi, but sadly we already know they are facing threats. It takes 40 – 50 years for mycorrhizal fungi to re-establish themselves after clear felling and climate change is starting to alter when they fruit. When we conserve our woodlands, we need to remember the importance of fungi.

By Jane Halliday

Please note that as the weather turns colder there will be less fungi around and if you are visiting the NNR please follow the British Mycological Society code of conduct for responsible collecting: https://www.britmycolsoc.org.uk/field_mycology/conservation/code-conduct

References:

Beechwood Sickener (Russula nobilis) – Woodland Trust

Bracket Fungi ID: Common UK Species – Woodland Trust

Fungi and Lichens – Woodland Trust

Oak trees and wildlife – Woodland Trust

wood-wise-fabulous-fungi.pdf (woodlandtrust.org.uk)

Ecology – Devon Fungus Group

Hyphae vs. Mycelium | Biology Dictionary

Mycorrhizal fungi / RHS Gardening

Saprophytic fungi / RHS Gardening

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