NATIVE RANGE: North America
FIRST FINDING IN SLOVENIA: not yet found in Slovenia
PATHWAYS: transported with infected wood, secundary spreadying also with wind and insects
POSSIBLE TO FIND: year-round
DESCRIPTION: The fruiting body is flattened, initially hemispherical, elongated, multi-annual, 1–30 cm wide. The upper layer is uneven, first reddish-brown, later on turning darker. With age, it eventually becomes black and only the growing edges maintain a white colouration. The hymenium on the underside is initially white, later off-white to yellowish-brown and has round or strongly elongated, irregularly-shaped pores (7.3 pores/mm2). In cross-section, the fruiting body shows several distinct layers.
HOST PLANTS: Infects coniferous trees. It rarely forms fruiting bodies on live trees, but often on tree stumps of infected trees and on dead or cut trees.
STATUS: Present in an area of about 100 km around the shore of Tyrrhenian Sea in Italy.
SIMILAR SPECIES: Three related fungi cause root diseases in Europe: Heterobasidion annosum, H. parviporum and H. abietis. They can be identified with a detailed investigation of their morphological characters (number of pores per mm2, the composition of fruiting bodies, shape of the edge, presence of hairs) and molecular techniques.