Elaphomyces granulatus

Description

Elaphomyces granulatus is an ascomycete fungus that grows in symbiosis with spruce trees, such that tiny mycelial threads from the False Truffle coat the tree’s rootlets to form what is known as mycorrhizas, and the tree and the truffle exchange various chemicals, each thereby assisting the other.

For humans E. granulatus are inedible and not tasty, especially older fruiting bodies are not edible. Since their fruiting bodies grow underground for this purpose, the commercial interest in the hypogeous genus Elaphomyces is very low.

The fruiting bodies consist of a relatively hard, rubbery bark and are filled with spores when mature. The rind usually has a wart-like texture and is light brown. The color and consistency of the spore material vary as the truffle matures. The initially light gray solid mass inside turns darker and darker as it matures. When fully ripe, the truffle is loose, powdery, and deep purple inside.

Common names: Deer Truffle, False Truffle.

Mushroom Identification

1. Fruitbody

   Irregularly globose, 2-5cm across; the thick outer skin is rufous-brown and covered in small (granular) warts. The interior spore mass is grey and moist initially, drying out and turning purple-black as the spores mature.

2. Spores

   Globose, 25-35μm; ornamented with rods and spines.

3. Spore Print

   Purplish black.

4. Habitat & Ecological Role

   Ectomycorrhizal, found most often under spruce trees but occasionally with other conifers.

History

When in his Systema mycologicum (1829) the great Swedish mycologist Elias Magnus Fries described the False Truffle he gave it the scientific binomial name Elaphomyces granulatus, and that is still its generally accepted scientific name.

Elaphomyces, the generic name, comes from Elaph-, meaning deer, and -myces meaning fungus (as in mycelium and mycology, for example). Fungi in this genus, and America Elaphomyces granulatus in particular, are sometimes referred to as 'Deer Truffles'. The common name Hart's Truffle has also been applied to this species.

The specific epithet granulatus relates in some way to a granular characteristic of the False Truffle, and specifically, it is a reference to the small granular warts on its outer rind.

Photo sources:

Photo 1 - Author: bjoerns (CC BY-SA 4.0)

Photo 2 - Author: Lamiot (CC BY-SA 3.0, 2.5 Generic, 2.0 Generic and 1.0 Generic)