Scientific name: Climacocystis borealis (Fr.) Kotl. &
Derivation of name: Climacocystis means growing in an
imbricate fashion like a staircase and having cystidia; borealis
means "northern" and refers to the northern range of this
Synonymy: Polyporus borealis Fr.
Occurrence on wood substrate: Parasitic and saprophytic;
solitary or as overlapping clusters at the base of and on roots
of living conifers and on logs and stumps; found year-round.
Dimensions: Caps 4-15 cm wide; 3-15 cm long; 0.5-4 cm
Upper surface: Whitish at first, yellowish in age; hairy; soft
and watery when fresh.
Pore surface: White, yellowish on drying; 1-3 per mm; pore
openings may be irregular and angular.
Comments: Climacocystis borealis causes a butt rot and
root rot of conifers. It continues as a saprobe on dead roots
and stumps. This species is circumglobal and boreal. It's
extends south in mountainous areas.
More information at RogersMushrooms.com:
Figure 1. An overlapping cluster of caps of Climacocystis
borealis. Photo © Dianna Smith.
Figure 2. Upper surface. Photo © Gary Emberger.
Figure 3. The color of the pore surface is about the same as
the upper surface. Photo © Gary Emberger.
Figure 4. Note the somewhat irregular shape of some of the
pores. Photo © Tom Volk.