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Species Information
Summary: Ganoderma oregonense forms large yellow-brown to red-brown semicircular or fan-shaped brackets with a lacquer-like surface, growing on conifers. Some authors consider this a synonym of Ganoderma tsugae.
Ganoderma oregonense is found in BC, WA, OR, ID, CA, MT, and NV, (Gilbertson).
Cap: up to 100cm parallel to substrate, projecting up to 40cm, up to 20cm thick, semicircular or fan-shaped; "yellowy brown to dark reddish brown or mahogany, with concentric bands of color; quickly develops a shiny, waxy crust that cracks extensively in older specimens", (Phillips), up to 100cm wide, 40cm deep, and 20cm thick, without a stem or with a rudimentary lateral stem, single or occasionally imbricate [shingled], annual; upper surface ochraceous to dark reddish brown or mahogany, often distinctly concentrically zoned; quickly developing shiny lacquered crust, crust cracking extensively on older specimens, (Gilbertson)
Flesh: up to 15cm thick, "soft-fibrous; cream-colored to pale buff", (Phillips), up to 15cm thick, "soft-fibrous, homogeneous and azonate or with a thin firmer layer with thin darker lines directly under the surface crust", cream-colored to pale buff, (Gilbertson)
Pores: 2-3 per mm, circular to angular; cream colored bruising brown or purplish brown; tube layer up to 3cm thick, pale purplish brown, (Phillips), 2-3 per mm, circular to angular, with thin entire walls; "cream colored at first, bruising or drying wood brown to pale purplish brown"; tube layer up to 3cm thick, distinct from flesh, pale purplish brown, (Gilbertson)
Stem: with no stem or small lateral stem-like attachment (Phillips)
Odor: none (Miller)
Taste: unknown (Miller)
Microscopic: spores 13-17 x 8-10 microns, elliptic, with truncate apex, inamyloid, pale brown in KOH, "wall with two layers separated by interwall pillars, outer wall with pronounced depressions and appearing rough"; cystidia absent; hyphal system trimitic: context generative hyphae 2.5-5 microns wide, "thin-walled, with clamps, rarely branched"; context skeletal hyphae 3-5 microns wide, colorless, thick-walled, non-septate, with occasional branching, context binding hyphae 2-4.5 microns wide, colorless, thick-walled, non-septate, with frequent branching, trama hyphae similar; cap surface with dense palisade of clavate, thick-walled strongly amyloid end cells, up to 70 microns long and 8.5-11 microns wide at widest point, (Gilbertson)
Spore Deposit: rusty brown (Phillips, Gilbertson)
Habitat / Range
annual, commonly on dead standing conifers and on conifer stumps, main substrates are Abies (fir) and Tsuga (hemlock), causes white butt and root rot of living and dead conifers, (Gilbertson), fruiting in spring, summer, and fall, (Miller)
Similar Species
Ganoderma tsugae is smaller (30cm x 20cm x 6.5cm), often has a well developed stem, has smaller pores (5-6 per mm), and has smaller spores (11-12.5 x 6.5-8.5 microns) (Ginns(28)). ''Very young specimens of Fomitopsis pinicola may be more or less completely "varnished" but the varnish disappears as the basidiocarp ages. The very dense, hard context of F. pinicola is very different from the light, soft-punky context of G. oregonense.'', (Ginns(25), with Latin names italicized). Ganoderma lucidum "is restricted to hardwoods and appears to be, at most, rare in the Pacific Northwest. Gilbertson and Ryvarden(1986) listed it from Oregon. There is one tentative British Columbia record of G. lucidum on Quercus garryana in Victoria.", (Ginns(28) with Latin names italicized). Ganoderma applanatum and Ganoderma brownii do not have a varnished appearance.
