Psathyrella aquatica

🏷️ Description

Mushrooms are usually associated with damp forest floors, hidden among fallen leaves or decaying logs. But Psathyrella aquatica defies the norm—it's the only known mushroom that fruits underwater! First discovered in 2005 in Oregon’s Rogue River, this unique fungus stunned the scientific community and was officially described as a new species in 2010.

🌍 A Hidden Gem of the Rogue River: Southern Oregon University professor Robert Coffan and his colleagues, Darlene Southworth and Jonathan Frank, stumbled upon this aquatic wonder while exploring the river. Initially met with skepticism due to its resemblance to other Psathyrella species, further research confirmed its uniqueness. In fact, less than 1% of aquatic fungi have been discovered so far, with most expected to be microscopic. P. aquatica, however, proudly stands up to 10 cm tall, fully submerged!

🌱 How Does It Survive Underwater?

The biology of P. aquatica is nothing short of extraordinary:

• It has a strong, hair-covered stipe (stem) that anchors deep into the riverbed, up to 1.6 feet (0.5 m) in sediment.

• Its brown convex cap houses gills that function underwater, a feature unheard of in gilled fungi!

• Spores released from the gills get trapped in gas bubbles, allowing them to float to the surface and spread—a brilliant adaptation to its submerged lifestyle.

• A 2014 study confirmed that P. aquatica only fruits when fully submerged in cold water, even when cultivated in lab conditions.

🏞️ A Unique Habitat

P. aquatica thrives in the clear, cold, spring-fed waters of the upper Rogue River. The conditions are key:

• Fast-moving, highly oxygenated water

• Woody debris, silt, and fine volcanic gravel as a growing substrate

• Depth of around half a meter

Interestingly, some specimens have been found on land, near the riverbank, on damp logs or gravel. However, in natural conditions, the mushroom has only been observed fruiting fully underwater.

🌋 The Role in Its Ecosystem

While its edibility remains unknown, scientists speculate that P. aquatica serves as a food source for aquatic insects, which in turn support fish populations. The river has low nitrogen levels, yet cyanobacteria near these mushrooms suggest they might contribute essential nutrients to the ecosystem.

🌟 A Scientific Marvel

The taxonomy of Psathyrella aquatica reflects its remarkable habitat—"aquatica" comes from the Latin word for water-related. DNA sequencing places it near species like P. atomata, P. fontinalis, and P. superiorensis, but its underwater adaptation makes it truly one of a kind.

This discovery opens exciting new avenues in mycology. If a fully aquatic gilled mushroom can exist, what other fungal secrets might be lurking in unexplored rivers and lakes? For mushroom hunters, fungi lovers, and scientists alike, P. aquatica is a reminder that nature still has many surprises waiting to be found.

So, next time you’re near a river, keep your eyes peeled—you might just discover the next great fungal mystery!