Tuber magnatum Pico. Weisse - Piedmont White Truffle

Taxonomy

Phylum: Ascomycota

Class: Pezizomycetes

Order: Pezizales

Family: Tuberaceae

Tuber magnatum, the Piedmont Truffle, grows in mycorrhizal relationship with the root systems of deciduous trees, mainly various Oaks and Hazel. In the city of Alba the annual White Truffle Fair and Market is held on weekends throughout October and iuntil mid November, terminating in a world truffle auction.

A massive Piedmont Truffle weighing 1.5kg was auctioned in 2007 and fetched a third of a million US dollars. Picture: Moi-meme (public domain)

Truffles are ascomycetes, which shoot their spores from flasks (asci, singular ascus)... but how can they do that when they form underground? The answer is thattruffles rely on animals digging them up and eating them. After the spores have passed through an animal's gut and have been excreted, they are able to produce a new myceliumthat has the potential to link up with the root system of a new tree and so allow growth and propagation of the fungal species.

Piedmont White Truffles are the most aromatic of all truffle species. Cut one in halves and it gives off a most distinctive (but un-mushroomy) smell. Pigs, dogs and other creatures with noses more sensitive than ours can smell them from above ground. This is why truffle hunters use either pigs or dogs to help them locate these delicacies.

Identification Guide

Description	There is no point in trying to describe the shape of a truffle: they are the ultimate in shapelessness. Blobs, occasionally more or less spherical but most often irregularly multi-lobed, the outer surface of a Piedmont Truffle (once any earth has been washed off) is creamy brown and rather like that of a potato. Inside, the cream or ochre spore-bearing material is marbled by white membranes in a random wandering form rather than any regular pattern.
Dimensions	Typically a few cm across and weighing 50 to 400g each, but exceptional specimens weighing over 1kg each are found.
Spores	Elliptical, 35 – 50 x 32 – 42 µm; reticulate; creamy white or yellowish in mass.
Habitat	Mycorrhizal with various oaks and poplars as well as Hazel and Beech, this rare mushroom is known to grow in the Piedmont area of northern Italy and in the Motovan Forest on the the Istria Peninsula in Croatia.
Season	Autumn
Occurrence	Being subterranean, these mushrooms are rarely seen by people walking in woodlands, and so their abundance and exact location is not readily available. The market is never flooded with White Truffles, and so the price remains very high indeed.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2011.

Dennis, R.W.G. (1981). British Ascomycetes; Lubrecht & Cramer; ISBN: 3768205525.

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.