Snorkeling for "The Rogue" Mushroom (by )

Mushroom of the Month: August, 2014

I guess it’s not so strange.  When the weather is hot and a little moisture is a pleasure, we head for the swimming hole.  Apparently Psathyrella aquatica has similar habits.

This small, drab mushroom would hardly be distinguishable from most other Psathyrellae species if it weren’t for its habit of fruiting underwater. This is most unusual behavior for a gilled fungus. Robert Coffan, an Adjunct Professor of water resources at Southern Oregon University, was vacationing with his family on the Rogue River. A bit of wading resulted in a surprise.  He discovered a new species. P aquatica in the Rogue River current.

Darlene Southworth who is a retired Southern Oregon University Biology professor confirmed the uniqueness of the species. In fact the species appears to be the only gilled mushroom species known to fruit under water. All specimens were permanently submerged in cold, spring-fed waters, not merely covered by rising water, and they continued to grow in the same area for 3 months.

Dubbed Psathyrella aquatica, the “Rogue Mushroom” was introduced to the broader scientific community in a 14-page paper submitted Nov. 9, 2007 to the science journal Mycologia. The paper was written by Jonathan Frank, a laboratory technician at SOU, in collaboration with Coffan and Southworth. It was named in 2010, but its range is still something of a mystery. P. aquatica showing bubbles forming on the mushroom's cap

So if you are vacationing and snorkeling in the upper Rogue River of Oregon, or for that matter any mountain stream in Northern California or Southern Oregon, keep an eye out for this little brown mushroom (LBM) that grows near submerged wood, and sometimes on river gravel.  It apparently has only been recorded between June and October from two locations on the Rogue. This mushroom is typically about 10 centimeters tall.  It has a small bell-shaped cap about 2 centimeters wide, a thin stipe and gills. Small bubbles adhere to the cap and stem.  Researchers have yet to identify the gas producing those bubbles. 

All this begs the questions: Are there other species that fruit under water?   How are spores dispersed?  What is the evolutionary history?

The attached sheet describes the mushroom, the habitats where it has been found, and provides instructions on what to do if you happen to actually find it. Essentially get coordinates and call Southern Oregon University to report the discovery…DO NOT PICK IT!). The sheet was given to the Jefferson Fish Society in hopes of establishing a range for the species.



Psathyrella Aquatica Search Guide for the Rogue Mushroom

Psathyrella aquatica

What We Know:

Fruiting from late June into October (see attached photographs of “typical” habitat).

Found on N Fork of the Rogue River.

Depth from near surface to 50 cm (20 in) below water surface.

Found in flowing water (not in backwater or stagnant area).

Observed on alluvium, on twigs, and among algae.

Cap: 1-2 cm (1/2 - 3/4 in) wide, buff-white to dark brown.

Stipe: 7-10 cm (3-4 in) tall, thin and spindly, breaks easily.

What We Surmise to be important conditions:

Constant baseflow (from springs rather than snowpack).

Constant, fairly cold temperature.

Submerged woody debris nearby (though sometimes found in bare alluvium).

Alder usually present nearby.

Hunting Suggestions:

Unlike the underwater close-up photos, these “little brown mushrooms” are small and hard to find, especially with rippling water.

Direct sunshine helps. 

If you find one, you will likely find another.

Slow down, look near debris at edges of a main channel, but still in flowing water near the banks or quieter shallow flow areas where silt can settle. 

What to Do Upon Observation:

Do not collect. Mushrooms degrade rapidly.

Note location (gps, USGS map, trail mile, whatever).

Photograph the specimen, and overview of the site, if possible.

Contact us! 

Robert Coffan 541-227-9024 <>
Jonathan Frank 541-890-7055 <>
Darlene Southworth 541-261-3775 <>

Psathyrella Aquatica habitat