What You Should Know
Tuber lyonii can be recognized by its orangish brown, relatively bald surface, its white-marbled interior, and its microscopic features—including gorgeous spores that are simultaneously spiny and reticulate. It is native to North America and is most commonly found in the southern United States in association with Pecan orchards although it also is found in native forests from Florida north into Quebec, Canada, and west to the Rocky Mountains. They are prized for their unique slightly musty, nutty aroma.
This white truffle has a thin buff-colored skin and can be slightly knobby with a marbled toffee & cream to the dark coffee-colored interior when ripe. They are used primarily as aroma and flavor accents in pasta dishes as well as in creole cuisine with a slight umami flavor.
The pecan truffle is so named because it is most commonly found in pecan orchards, in association with the pecan tree, however, the pecan is not its only symbiote. It is most commonly reported in association with Carya (hickories and pecans) and Quercus (oaks, the most receptive of Tuber symbiotes). However, it has occasionally been discovered in association with Corylus (hazels) and Castanea (chestnuts), and even Basswood trees.
Fruiting bodies seem to be produced most prolifically on young trees, and fruits towards the end of summer and into fall depending on the specific local climate. In the southernmost part of its range through Florida and southern Georgia, fruiting may continue through the winter and as late as February. The fruiting bodies can reach up to 12 centimeters across at maturity, though most fall between 0.5 and 2 centimeters.
Other names: Pecan Truffle, American Brown Truffle.
Tuber lyonii Mushroom Identification
Mycorrhizal with oaks and hickories (especially pecan); growing alone or gregariously underground, often in disturbed-ground and urban settings; summer and fall, or overwinter in warm climates; primarily southeastern in distribution but reported throughout eastern North America and in New Mexico.
1–4 cm across; more or less round, but lumpy and irregular; outer surface bald, dry, smooth with slightly roughened areas, orangish brown; lacking a stem; outer skin 3–4 mm thick; interior flesh watery grayish, marbled with white lines and spots, fairly firm. Odor is strong, truffle-like.
Spores 28–32 x 15–18 µm excluding ornamentation; ellipsoid; densely spiny with spines 1–3 µm long; also reticulate with low connecting lines; thick-walled; yellowish-brownish in KOH. Asci 50–70 µm across; subglobose to ellipsoid; 1- to 4-spored. Inflated cells of epicutis 5–10 µm wide.
Tuber lyonii Look-Alikes
Several other species of truffle-like fungi that can superficially resemble the pecan truffle are common in pecan orchards and oak woodlands. Fortunately, there are key differences that can be used to successfully identify any ‘imposter fungi’ and differentiate them from the true pecan truffle. For instance, species of Hymenogaster (“false truffles”) usually have a radish-like odor and porous internal tissues that resemble a brown-colored sponge (Figures 3A and B). Scleroderma species (also called “earthballs”) can be confused with pecan truffles. However, specimens of Scleroderma always have white fungal cords (rhizomorphs) that are attached at their bases, and they also have purplish-black spore masses that are powdery at maturity (Figures 3C and D). A third look-a-like is the genus Pisolithus (dead man’s foot). Species of Pisolithus always have a distinct base and variously colored chambers within the fruiting body that become brown and powdery at maturity (Figures 3E and F). These fungal features are very distinct from the meandering pale veins and solid interior of the pecan truffle.
Tuber lyonii Synonyms
Tuber texensis Trappe (1996)
Tuber texense Heimsch (1959)
Photo 1 - Author: johnplischke (Attribution-NonCommercial 4.0 International)
Photo 2 - Author: johnplischke (Attribution-NonCommercial 4.0 International)