Tuber aestivum Vittad. - Summer Truffle

Taxonomy

Phylum: Ascomycota

Class: Pezizomycetes

Order: Pezizales

Family: Tuberaceae

Tuber aestivum, the Summer Truffle, grows in mycorrhizal relationship with the root systems of Beech trees on lime-rich soil.

The variety of Summer Truffle found in Britain and other northern European countries is sometimes referred to as the Burgundy Truffle, Tuber aestivum var. uncinatum. The Burgundy Truffle was formerly treated as a separate species, Tuber uncinatum, but molecular analysis has shown that the Summer Truffle and Burgundy Truffle are the same species.

Differences in taste and odour were the original reasons for the two forms of Tuber aestivum being treated as separate species. Even their spores displayed some morphological distinctions, but it is now believed that all of these differences are due solely to ecological rather than evolutionary factors.

Picture courtesy www.plantin.com

Identification Guide

Description	The fruitbodies are usually more or less spherical but occasionally irregular and multi-lobed; the outer surface is dark brown or black and covered in irregular pyramidal warts. Inside, the spore-bearing material is initially white, becoming beige or grey-brown and marbled by white membranes in a random rather than regular pattern.
Dimensions	Typically 3 to 6cm across but occasionally much larger.
Spores	Egg-shaped, 20 – 45 x 18 – 35µm; ornamented with a coarse irregular reticulum; creamy white or yellowish in mass.
Habitat	Mainly under Beech trees but very occasionally under oaks, always on alkaline soil. Like other edible truffles the Summer Truffle is found mainly in southern Europe, although its northern spread is such that these truffles can be found by diligent searchers in many more countries including Britain and even Scandinavia.
Season	Harvesting is from early summer until mid autumn, although in mild winters it is possible to find Summer Truffles as late as the beginning of January.
Occurrence	Being subterranean, these mushrooms are rarely seen by people walking in woodlands, and so their occurrence is a matter of conjecture (or of commercial secrecy if you are a truffle merchant!).

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.