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Species Information
Summary: {See also Trametes versicolor and similar polypores Table.} Features of Trichaptum abietinum include 1) thin, tough, shelf-like or bracket-like fruitbodies that are whitish to grayish on the upper surface and usually concentrically zoned, 2) purplish pore surface that fades to ochraceous and becomes tooth-like, and 3) growth on conifers. It is very common in the Pacific Northwest. On hardwoods, compare with the common Stereum hirsutum (no pores on underside - see Crust category) and the common Trametes versicolor. Neither have purple color on the underside. "The purple, toothed lower surface make[s] this common polypore immediately recognizable. The purple colours fade with age, but the small, thin, soft, white pilei and occurrence on conifers strongly suggest T. abietinum" (Ginns).
It is found in BC, WA, OR, ID, AB, MB, NT, NB, NF, NS, ON, PE, PQ, SK, YT, AK, AL, AR, AZ, CA, CO, CT, DE, FL, GA, IA, IL, IN, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NH, NJ, NM, NV, NY, OH, PA, SC, SD, TN, TX, UT, VA, VT, WI, WV, and WY, (Gilbertson), and Europe and Asia, (Breitenbach).
Cap: 1-4cm broad, shelf-like or bracket-like, fan-shaped to kidney-shaped or elongate, "tough and leathery when fresh, rigid when dry"; white to grayish, but when old often greenish from algae or blackish; "dry, covered with coarse stiff hairs", "usually concentrically zoned or grooved"; margin often wavy, (Arora), usually bent outward from a pore surface (which is growing flat on wood) to form shelf-like cap, but sometimes bracket-like or entirely flat on wood, caps up to 1.5cm broad, 8cm along wood, 0.2cm thick, single or imbricate [shingled], often laterally fused; gray; hirsute [hairy], smooth, not zoned, (Gilbertson)
Flesh: up to 0.1cm thick, tough; "pale gray to brownish or purplish", (Arora), usually less than 1cm thick, duplex, the upper layer soft, floccose, whitish, the lower layer firm, tough-fibrous, white, (Gilbertson)
Pores: 2-4 per mm, round to angular but when old often irregularly torn or tooth-like; "whitish to brownish but usually tinged bright lavender to purplish when fresh, especially toward cap margin", duller or browner when old; tube layer up to 0.3cm thick, (Arora), 4-6 per mm, angular, with thick walls that become thin and deeply torn when old; "bright purplish, fading to ochraceous"; tube layer up to 0.15cm thick, colored as the lower layer of flesh and continuous with it, (Gilbertson)
Microscopic: spores 6-7.5 x 2.5-3 microns, cylindric, slightly curved, smooth, inamyloid, colorless; basidia 4-spored, 12.5-14 x 5-6 microns, clavate, with basal clamp; cystidia abundant, 4-7 microns wide, embedded or projecting to 15 microns, arising from tramal skeletal hyphae that curve out into hymenium, usually capitately incrusted; hyphal pegs also present; hyphae dimitic, skeletal hyphae of context 2.5-5 microns wide, colorless, thick-walled, with rare branching, nonseptate, generative hyphae of context 2-4 microns wide, colorless, thin-walled, rarely branched, with clamp connections; hyphae of trama similar, (Gilbertson), spores 4-8 x 2-4 microns, cylindric or sausage-shaped, smooth, (Arora)
Spore Deposit: whitish (Arora)
Habitat / Range
annual, in groups, shelving masses, or overlapping tiers on decaying conifers, (Arora), annual, on dead sapwood of conifers, reported to be occasional on hardwoods; associated with white pocket rot of dead sapwood of conifers: "pockets are hollow and the wood becomes fragile and lacy in the late stages of decay", (Gilbertson), may be seen year round (Bacon)
Similar Species
Trichaptum biforme is similar, but grows on hardwood slash: fruiting bodies tend to be much wider, are usually attenuated to a narrow base, and have a tomentose or bald upper surface and a pore surface that more quickly becomes faded and tooth-like, (Gilbertson). Trichaptum subchartaceum differs in having much thicker fruitbodies and a persistently poroid lower surface, and it is restricted to Populus, (Gilbertson). See also SIMILAR section of Skeletocutis amorpha and Trichaptum laricinum.
