Rhizopogon obtectus

There is no true cap. The fruiting body is tuber-shaped, round or irregularly round, 1 to 4 centimeters across, resembling a small potato or a truffle. The surface is smooth or covered with fine pressed-down fibers (rhizomorphs), whitish or yellowish at first, turning reddish-brown or olive-yellow with age and where handled. The entire fruiting body is closed, with no openings.

There is no hymenophore in the usual sense. The spores ripen inside the closed fruiting body, in a maze-like chambered tissue (the gleba). In young mushrooms it is white and firm; as it matures it turns yellow, then brown and jelly-like, and later powdery. The spore print is olive-brown. A chambered inner tissue with no true pores or gills is a hallmark of the underground rhizopogons.

There is no distinct stem; the fruiting body is attached to the soil by thin whitish cords (rhizomorphs), especially noticeable at the base. The whole structure is a single solid tuber with no division into cap and stem, which is exactly what sets Rhizopogon apart from the familiar cap-and-stem mushrooms.

The flesh (gleba) of young mushrooms is white, firm and uniform, with tiny maze-like chambers. This is the only stage at which the mushroom is edible. As it matures, it turns yellow, then brown, becomes jelly-like and unfit to eat. White young flesh in cross-section is your guarantee of edibility; any darkening means the mushroom is overripe.

The smell is faint, pleasant and mushroomy, becoming stronger and not always pleasant in mature specimens. The aroma is not a defining feature; you recognize this mushroom by its underground lifestyle, its closed tuber-like fruiting body with no cap or stem, and its link to pine.