The split gill: the toughest mushroom in Europe, and why it grows everywhere

It sits somewhere on almost every dead branch: a fan of one to four centimetres, greyish white, finely hairy, with gills on the underside that are split lengthways. The split gill, Schizophyllum commune, is so ordinary nobody looks at it. That is a shame, because it is one of the most remarkable organisms you can find on wood, and the only species in our range we sell for reasons other than the pan.

Why does it grow everywhere?

The split gill occurs on every continent except Antarctica, on almost any wood, from oak to palm, and even on straw bales, old books and, in one famous case, the hull of a ship. The secret is its drought resistance. A split gill can dry out completely, hang on a branch as a hard flake for months or even years, and after a shower swell back up within hours, unfold its gills and release spores. Few other mushrooms can do that. On top of that, the species has more than twenty thousand different mating types, so almost every encounter between two split gills is a fertile one. It is an organism built to be absent from nowhere.

Is the split gill edible?

Yes and no. In Europe it counts as inedible, not because it is poisonous, but because it is as tough as leather. In parts of India, Indonesia, Thailand and Mexico it is eaten: long-stewed in curries and soups, or dried and chewed as a kind of savoury snack. Anyone trying it must cook it for a long time and not expect a meaty bite. It is more a seasoning or a texture than a meal. Honestly, this is not a species you grow to eat, and we do not sell it as one.

So why would anyone grow it?

For three reasons. The first is curiosity: the split gill is a model organism in mycology, one of the best-studied fungi in the world, and watching it grow on your own log, dry out and come back to life teaches more about how fungi work than any book. The second is research and interest in its compounds: schizophyllan, a beta-glucan used medically in Japan and the subject of much research, is extracted from the split gill. The third is practical: the split gill colonises wood other species leave alone, including thin branches and wood chips, which makes it a rewarding first tenant for a dead hedge you want to see come alive quickly.

An honest caveat

The split gill is also known in the medical literature as a rare cause of infections in people with severely weakened immune systems, usually in the sinuses or lungs. For healthy people that is no concern, the spores drift literally everywhere and nobody escapes them. But anyone with a seriously compromised immune system is better off not growing this species indoors and not hovering over a cloud of spores. We mention it because we would rather say it once too often.

How do you grow the split gill?

Like any wood fungus, only easier. Plug spawn in fresh wood, any broadleaf works, thin branches of five centimetres are already enough. Drill, tap in the plugs, seal with wax, lay in the shade. The split gill is fast: often the first fans within six months, then years on end, peaking after every wet spell. It is the species that asks the least patience of anything we sell, and the one most often overlooked because it is so small.

Who is this for?

For the curious, the collector and the teacher. For anyone who wants to bring a wood pile to life quickly. For anyone interested in what fungi can do beyond the kitchen. Not for anyone who wants a harvest: take an oyster mushroom instead. But once you have watched a piece of wood full of split gills swell up in the rain, you look at every dead branch in the forest differently. That is worth something too.