Hard Summer Rains Bring Desert Mushrooms

Desert shaggy-mane | Photo: Bryant Olsen/Flickr/Creative Commons License

You expect certain kinds of living things in the desert. Scaly, occasionally venomous reptiles, plants with fierce armor, swift and clever animals accustomed to dealing with heat and drought.

But mushrooms?

That's what KCETLink staff member Jeremy Howard found, much to his surprise, when he went out to check the station's Palm Springs transmitter after a bout of heavy rains had damaged roads leading to the facility.

And poking up through one of those damaged roads was a species you might more easily expect in a soggy redwood forest or coastal prairie.

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Jeremy snapped a photo and sent it in to ReWild with this note:


Here's the photo Jeremy sent along:

Desert shaggy mane on Edom Hill | Photo: Jeremy Howard

Jeremy's find is one of those desert sightings that's both unusual and commonplace at the same time. It's a desert shaggy mane mushroom, Podaxis pistillaris, a species found in deserts and other dry places around the world. Related to puffballs, the desert shaggy mane gets its common name from its resemblance to another common mushroom, the shaggy mane or Coprinus comatus.

Despite the resemblance, the desert shaggy mane is distinctly different from its namesake. The Coprinus shaggy mane, also called "inky cap," grows in moist environments and dissolves into a black liquid when its microspoic spores are ready to release. The desert shaggy mane just dries out, hardens, gets blown around the desert by wind, and releases spores when it develops cracks.

Those spores are the secret to how the desert shaggy mane can be both common and a rarity at the same time. The above-ground living things we call mushrooms or toadstools are just a tiny part of the organisms they belong to. They're fruiting bodies; in other words, they're that part of the fungus that grows under certain conditions to develop and release spores so that new fungi can be born.

When they aren't fruiting, fungi are still there: they live as a mass of tendrils called "hyphae" (pronounced "high-fee"). Most fungal hyphae grow in the ground or in decaying organic matter, though some are parasitic, growing in living tissue.

In the case of Podaxis pistillaris, those hyphae grow in loose desert soils, especially at the bases of trees in washes. As small amounts of moisture reach the hyphae, they grow slowly, interweaving themselves a few inches below the surface and consuming whatever organic matter they can find.

Pretty much wherever you go in the California desert, desert shaggy manes are growing. We just don't see them, except in conditions like those Jeremy encountered: just after a heavy rain. When the desert shaggy mane's hyphae get a really big water supply, that signals their genetic programming that it might be a good time to make some spores.

It's not that the spores need to land on the wet ground to grow into new hyphae: by the time they're released, that water might well be gone. In any event, fungal spores can live for many years in the absence of water. All they need to do is wait for a storm in a month -- or a decade -- and then start sending new hyphae through the soil.

The reason desert shaggy manes send up fruiting bodies after a good rain is that making those fruiting bodies, even fibrous and tough ones like the desert shaggy mane's, takes water -- and water is almost always in too short supply in desert soils for the fungus to use for anything but survival. Once a surplus comes, that's when you can spend it making mushrooms.

That tough and fibrous fruiting body means that desert shaggy manes are considered inedible, probably a smart strategy in a desert full of hungry coyotes and rabbits and rodents. No one wants to eat them, so they get to roll around the desert for months distributing spores here and there.

It's just another example of how species that live in the desert can be all over the place, right under our noses, and yet escape our notice unless we're in the right place at the right time.

For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.

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