Ascomycetes Wannabes: Cyphelloid Fungi—Part I

A few days ago I found a pale resupinate fungus growing on the side of a very rotten, mossy log up near Algonquin Park. Log-clinging fungi can be difficult to identify. There are a lot of them, and, outwardly, the majority are not particularly exciting. I took out my loupe to see if this one had anything fun going on—teeth, for instance, or velveteen bumps, or rubbery undulating ridges. I got something better, so much better that I actually did a double take: crowded on a cream-coloured cottony blanket were thousands of itsy-bitsy cups. Cups!

Porotheleum fimbriatum can produce thousands
 of tiny cups on a cottony subiculum. Click to see large.

Now, here's the thing—cup-shaped fungi are almost always ascomycetes that produce ejectable spores in asci. They can be big or tiny, hairy or smooth. They can be bright coloured or dull, stemmed or completely sessile. They can grow singly or scattered or in large clans. What they don't usually do is grow from an easy-to-peel-off cottony blanket half a metre long. 

Parts of the soft fruiting body of P. fimbriatum had engulfed mosses.

What I'd found was not an asco, but a peculiar basidiomycete called Porotheleum fimbriatum (also Porothelium fimbriatum or Stromatoscypha fimbriata).

The cups of P. fimbriatum are only 0.1-0.2 mm wide. They
can eventually become so crowded they resemble pores.

Porotheleum fimbriatum belongs to small group of cup-, disc-, or tube-shaped basidiomycetes that were once all lumped together in the genus Cyphella. By the end of the nineteenth century, however, enough differences had been noted between these tiny guys that most of the 300 described species had already been divvied up into a number of new genera.  

Cup-shaped cyphelloid fungi include Merismodes species.

It has long been proposed that these cyphelloid cups and tubes are "reduced forms" of much more "mushroomy" fungi. Evolution does not insist on making things ever more complex; sometimes an evolutionary trend is towards simplification. Many flowers that first evolved to form complicated collections of stamens and pistils have since progressed into simplified, or "reduced forms," in some cases paring down their reproductive organs to such an extent that they produce only a single stamen per male flower and a single pistil per female, a much more efficient use of a plant's resources. 

Examples of reduced-form evolution among vertebrates include animals whose ancestors had four limbs, but that are now either missing hind limbs or have no limbs at all, such as manatees, whales, snakes, and a few lizards.  

Anguis fragilis, a legless lizard (Lameiro)

In the case of reduced-form cyphelloid fungi, DNA sequencing shows some eye-opening connections with other species. Take, for instance, my strange fungal find P. fimbriatum. Molecular studies demonstrate that one of its very close siblings is Hydropus fuliginarius (Moncalvo et al, 2002). Other than H. fuliginarius's characteristic of producing a blackening latex, this rare little guy looks just like a normal mushroom, with cap and stem and gills. Who would have guessed it could have such an unlikely sister? Without sequencing, the only similarity between the two is that they're both saprophytes, obtaining their energy from rotting trees. 

Hydropus fuliginarius (Renée Lebeuf)

I've found other cyphelloid fungi—and almost every one has looked so much like an ascomycetes cup that I've been tricked into flipping first through my asco books before a lightbulb has gone off, sending me to where I should have been looking in the first place, in my basidiomycetes references. I'll deal with a few more of these curiosities in a couple of weeks, including one that has an even weirder sibling than P. fimbriatum.

References:

Porotheleum fimbriatum, CBS—KNAW Fungal Diversity Centre

Cyphelloid fungi

Hydropus fuliginarius, Mycoquebec

P. Bodensteiner et al. (2004). Phylogenetic relationships of cyphelloid homobasidiomycetes. Molecular Phylogenetics and Evolution 33(2):501-15.

Moncalvo, J. M., et al. (2002). One hundred and seventeen clades of euagarics. Molecular Phylogenetics and Evolution 23: 357–400
Peter Werner, 2004. Fungal Taxonomy III: The Euagarics. Mycena News.
Dick Rauh. Reduction and Fusion - Flowering Evolution. The Botanical Artist, Volume 13, Issue 1.

A Multi-use Forest Candelabra: Polyporus umbellatus

Two days ago I was out in the woods on a mission: to stock up on enough chanterelles to last us through the winter. It's a job, so I have to give myself rules: pick them as quickly and efficiently as possible, then get them home. No distractions allowed. Period. Focus only on those glowing patches of orange. I didn't even bring my loupe.

Unfortunately, I'm easily distracted. I'm also not good at following rules. I was squatting in the middle of a fairy ring of chanterelles when I spotted a bright incongruity to my left, a pale brown fungal bouquet blossoming from the forest floor. To hell with the chanterelles—I'd found something way more exciting, a pristine patch of Polyporus umbellatus, the Umbrella Polypore. I've only seen this rarity once before, when my friend Ulli brought me a very wormy, decaying specimen to identify, so I was thrilled to find a bunch of it in its prime. Now I could taste it.

The caps are 2-3 cm., umbilicate, and have tiny scales.

At first glance, it might be possible to mistake P. umbellatus, for a young Grifola frondosa, or Hen-of-the-Woods, since its multiple caps can be the same smokey brown as those of "hens," but the similarity ends there. While G. frondosa makes large rosettes of petal-shaped caps, P. umbellatus forms a more delicate candelabra made up of tiers of small, white-stemmed "mushrooms," each with a nearly circular pileus, all sprouting from a solid whitish core. P. umbellatus also grows very early in the season, in June and early July, while G. frondosa appears in the fall.

Close-up of the irregular pores of Polyporus umbellatus

But the most interesting difference between these two choice edibles is the way P. umbellatus (also known as Dendropolyporus umbellatus and Grifola umbellata) grows. Though, like G. frondosa, it's associated with hardwoods, in particular, with oaks, the fruiting body arises not from the base of trees, but from underground sclerotia, and often appears a distance from the closest tree. 

Sclerotia are lumpy structures made up of densely packed masses of hyphae that can withstand adverse conditions, sometimes for many years. In the case of P. umbellatus, this hard sclerotium only seems to form in symbiotic association with various Armillaria, or honey mushroom species. For most of the year it's as hard as wood, but early in the season it absorbs water and softens, and from it sprouts the fruiting body that can reach 50 cm. in diameter.  

Polyporus umbellatus sclerotum (Brandon Searcey, Mushroom Observer)

P. umbellatus sclerotia have been dried and used medicinally in China for at least two thousand years. Known there as Zhu Ling, or "Hog Tuber" because of its resemblance to pig dung, its traditional use has primarily been as a diuretic. More recently, though, research has been more focussed on the antitumor and immunomodulating properties of polysaccharides that can be extracted from the sclerotia. Other compounds are being studied for their immunostimulating, anti-inflammatory, and hepatoprotective properties. In vitro inhibition of the malaria parasite, Plasmodium falsiparum, has also been reported.

The candelabra or bouquet structure of the umbrella polypore.

Though this extraordinary fungus grows in northern hardwood forests around the world, it is not common anywhere, and, because of the fast-growing interest in its medicinal qualities, it has been over-harvested, so much so that in some areas it is reportedly in danger of extinction. This has led to current research on cultivating the sclerotia under artificial conditions. 

For my part, since each underground sclerotium can apparently produce fruiting bodies for years to come, I will leave that portion of the organism in place so I can return early each summer to collect some more of this delectably tender and tasty polypore for the table. 

Tender, delicate, mushroomy tasting morsels.

References:

Polyporus umbellatus on MushroomExpert.com  
Polyporus umbellatus on Mycoquebec
Paul Stamets, Mycelium Running, Ten Speed Press, 2005
Christopher Hobbs, Medicinal Mushrooms, Botanica Press, 2003
Yong-Mei Xing, et al, Sclerotial Formation of Polyporus umbellatus by LowTemperature Treatment under Artificial Conditions, PLoS ONE; 2013, Vol. 8, Issue 2, 1

Gen  Kikuchi, Hiroki Yamaji, Identification of Armillaria speciesassociated with Polyporus umbellatus using ITS sequences of nuclearribosomal DNA, Mycoscience, Vol. 51, Issue 5, 2010, 366-372