A hidden world of fungal cords

Next time you crunch or squelch through a rich leaf litter under trees, stop and get your eyes down to the forest floor. Carefully tease apart the rotting leaves, twigs and decaying branches and you may be lucky enough to see some fungal or mycelial cords.

Fungal cords running between a rotting silver birch log and the leaf litter on the forest floor
Fungal cords running between a rotting silver birch log and the leaf litter on the forest floor

Quite a number of saprotrophic fungi, particularly the wood-decaying Basidiomycetes (e.g. including some of the stinkhorns, bracket fungi, or puffballs), can form mycelial cords. Cords are collections of  hyphae that aggregate to form long cords. These cords can create vast webs across the floors of forests, in both temperate and tropical regions, where they link nutrient resources together.

Fungal cords and hyphae on a decomposing silver birch log on the forest floor
Fungal cords and hyphae on a decomposing silver birch log on the forest floor. One cord can be seen top right linking to the leaf litter. Bottom left, visible as a network of dark strands, are probably the cords of the Honey Fungus Armillaria mellea

The cords can be visible as creamy white strands, varying in thickness from thin cotton threads to chunky spaghetti. Carefully roll over a well-rotten log (don’t forget to roll it back afterwards) and you may see cords running from the leaf litter on the forest floor, and onto and into the log . Sometimes you may find rotting leaves stuck together by tiny nets of white threads. Cords also travel at the surface of the soil, running along underneath a carpet of leaf litter, where you can track them to their source; often a substantial rotting log.

Fungal cords running along underneath the leaf litter
Fungal cords running along underneath the leaf litter (cleared away for the photograph). The cords rarely penetrate the soil.

It is thought that fungal cords play an extremely important role in recycling carbon and mineral nutrients, but little is actually known about their diversity and behaviour; for instance it is thought that fungi species that form cords can be highly competitive. Their ability to redistribute nutrients across the forest is extremely important but only just beginning to be understood and appreciated.

Gabriel Hemery


These photographs were taken during fieldwork where I was assisting the Sylva Foundation’s scholar, Kirsty Monk, in her DPhil research programme read more

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