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