Immature specimens, such as the one shown here, are downy and pale yellow. As the fruiting body matures, the cap, which expands to between  8 and 14 cm (exceptionally 20 cm) in diameter, becomes dull yellow-brown. The yellow cap flesh turns blue-black if it is cut or bruised.

Beneath the cap, yellow spore tubes terminate in tiny circular pores that are at first yellow but eventually turn orange-red.

Pores :  At first yellow, soon red, paler orange-yellow to cap margin; turn blue when bruised. Tubes yellow, bruising blue when exposed, in age olive; cap context above tubes yellow; depressed at stipe; 10-30 mm long.

Stipe : 

1.5 to 4 cm in diameter and 5 to 10 cm tall, the swollen stem turns dark blue when cut and then fades back to a light blue colour, as seen here. The flesh near the base of the stem is deep yellow with red tinges.

The surface of the stem is yellow, covered with a red mesh patterning everywhere except for the  top of the stem, which remains yellow. 

Most commonly found under beech trees on calcareous soil, this species is also occasionally seen beneath oak trees and limes.

July to late October.