Polyporus tuberaster
Description
Polyporus tuberaster grows on fallen branches of deciduous hardwood trees. It is reported that sometimes these funnel-shaped polypores grow from a sclerotium-like tuber (a hard mass of mycelium that stores food reserves, enabling the fruitbody to survive harsh environmental conditions). It occurs also across most of mainland Europe and in many parts of Asia.
These woodland fungi are easily overlooked, as often the caps are darker than those on the left and blend in with a background of dead leaves.
When young the fruitbodies of the Tuberous Polypore are said to be edible and quite good.
Mushroom Identification
Cap
5 to 10cm across; round rather than bracket shaped; slightly or deeply funneled; light brown to dark orange-brown and covered in small scales, sometimes concentrically zoned; the thin margin is often downturned or inrolled.
Stem
Rudimentary, pale; reported to be attached to a sclerotium in some instances (but certainly not generally so in Britain and Ireland); hairy near the base.
Tubes and Pores
Tubes are creamy-white, 1-4mm deep, terminating in white or cream angular pores spaced at 1-3 per mm, decurrent and so leaving very little bare stem.
Spores
Cylindrical, smooth, 12-16 x 4-6µm; inamyloid.
Spore Print
White.
Odor and Taste
Odor slightly mushroomy; taste mild but not distinctive.
Habitat & Ecological Role
Saprobic, most often found growing on buried rotten hardwoods, particularly Beech.
Season
Summer and autumn.
Similar species
Dryad's Saddle, Cerioporus squamosus, occasionally forms trumpet-shaped fruitbodies arising from roots under the leaf litter; however, it has a black stem base and larger cap scales than the Tuberous Polypore.
History
The Tuberous Polypore was described in 1796 by Dutch naturalist Nicolaus Joseph von Jacquin (1727 - 1817), who gave it the binomial scientific name Boletus tuberaster. It was the Swedish mycologist Elias Magnus Fries who, in 1821, redescribed this species and transferred it to the genus Polyporus, thus establishing its currently accepted scientific name Polyporus tuberaster.
Synonyms of Polyporus tuberaster include Boletus tuberaster Jacq., Favolus boucheanus Klotzsch, Polyporus lentus Berk., Polyporus coronatus Rostk., Polyporus floccipes Rostk., Polyporus boucheanus (Klotzsch) Fr., and Polyporus forquignonii Quél.
The generic name Polyporus means 'having many pores', and fungi in this genus do indeed have tubes terminating in pores (usually very small and a lot of them) rather than gills or any other kind of hymenial surface.
The specific epithet tuberaster means 'with tubers', and in the case of the Tuberous Polypore this is a reference to tuber-like lumps of hyphae from which these funnel-shaped fungi emerge.
The tubers are reputed to store essential food substances necessary for the fungi to survive in harsh environments. Round, oval or irregular in shape, the tubers are ochraceous and fleshy when fresh, shrinking considerably if they dry out.
Other polypores that either mainly or at least sometimes have central (or nearly central) stems include Polyporus brumalis, and Phaeolus schweinitzii as well as some of the bracket fungi - particularly in the genera Trametes, Bjerkandera, and Meripilus.
Photo sources:
Photo 1 - Author: dschigel (CC BY-SA 4.0)
Photo 2 - Author: Adam Bryant (CC BY-SA 4.0)
Photo 3 - Author: Enrico Tomschke (CC BY-SA 4.0)
Photo 4 - Author: amadej trnkoczy (amadej) (CC BY-SA 3.0)
