The Piggyback Pinkgill: The Mushroom Mushroom-Parasite Volvariella surrecta

Last week's Mycological Society of Toronto foray was a wet one. It rained for hours. Despite the amount of water that was falling from the sky, there were slim pickings since it's been unseasonably and unreasonably dry for months. 

Because of this dearth of fungi, I was doing a quick last minute gleaning of the woods beside the parking lot hoping to add to the meagre display on the identification table when—through my dripping glasses—I spotted a tight clump of whitish mushrooms among the fallen leaves. My first thought was that they were Coprinoid. Knowing that I wouldn't be bringing it home if they weren't easily identified (I knew they'd liquify before I'd have time to get to them), I just roughly grabbed a couple as a sample. 

The first engraving of Volvariella surrecta by John Leonard
Knapp, 1829, showing strangely unaffected hosts.

The host of the ones I found, Leucopaxillus albissimus,
was barely recognizable as a mushroom.

Since the mushrooms came up attached to a squidgy piece another, larger mushroom, I knew before I even straightened up what I'd found: Volvariella surrecta (though its name escaped me and I had to be reminded of it by Nathaniel, our club's 13-year-old budding myco-meister!). Nonetheless, it was a joyful moment—but a sad one, too. Joyful because I've been wanting to find this character for nearly a quarter century. But sad because the specimens were pristine, with multiple stages of development—which would have been the perfect set-up for photography of a rare species. If I hadn't thoughtlessly wrecked its display. Dang!

Volvariella surrecta emerges from a well-developed volva, or cup.

Volvariella surrecta is one of very few mushrooms that grow on other mushrooms. It's pretty picky about who it grows on—primarily on Clitocybe species, but occasionally Tricholoma. Apparently in western North America and in Europe. Its preferred host is Clitocybe nebularis, which is not found in eastern North America. 

Volvariella surrecta is usually found on Clitocybe nebularis. (Wikipedia)

There's some dispute about whether it's an obligate parasite or if it's sometimes simply saprobic on its hosts. Some host fungi are considerably deformed, but are otherwise solid, while others, like mine, are decaying messes. I should say that I had a devil of a time finding any spores on the seemingly undistorted gills of the Leucopaxillus albissimus that mine had chosen to grow on. I eventually found a dozen are so. I have no idea if they would have been viable or not. 

Though rare, Volvariella surrecta is easy to recognize.

There were lots of little nubbin babies waiting in the wings.

On-line References for Volvariella surrecta:

on Mycoquebec

on Scottish Fungi (are the Scots responsible for the common name "Piggyback Pinkgill")
Arthur Henry Reginald Buller (1924) Researches on Fungi: vol. 3