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Species Information
Summary: Features include 1) a fruitbody that is variable in shape and size, and is bracket-like, or top-shaped or rosette-like with a central or lateral stem, 2) a cap that is whitish to pale brown, 3) flesh with an upper spongy layer and a lower firm layer, 4) light buff pores that are angular to maze-like, 5) a tendency of the fruitbody to turn red-brown when handled or injured, 6) a tendency of the fruitbody to incorporate pieces of plants, and microscopic characters. Abortiporus biennis is unusual in producing chlamydospores on various parts of the fruitbody (for instance the cap and the stem). A distorted form occurs with no apparent orientation of tubes and may appear poroid over the entire surface.
Abortiporus biennis has been found in BC, WA, OR, ON, PQ, AL, AZ, CA, DE, FL, GA, IA, IL, IN, KY, LA, MA, MD, ME, MI, MO, MS, NC, NE, NJ, NY, PA, OH, TN, TX, and WI, (Gilbertson).
Cap: up to 15cm in diameter, usually single, sometimes imbricate, almost circular to semicircular; whitish to pale brown, not zoned or faintly zoned, margin the same color; tomentose, shallowly sulcate [grooved] or appressed-fibrillose around margin, (Gilbertson), 8-20cm across, top-shaped to rosette-like; whitish when young, later ocher to brownish; smooth, slightly undulating to somewhat pitted, finely velvety-tomentose; margin thin, wavy-lobed, in part crenate [scalloped], "lighter to white, spotting red-brown when handled"; fruitbody usually incorporates pieces of plants, (Breitenbach)
Flesh: up to 0.8cm thick, upper part soft-fibrous, light buff, lower part firm-corky, cream-colored; tube layer up to 0.6cm thick, colored as lower flesh and continuous with it, (Gilbertson), about 0.5cm thick, duplex, hard within and soft on the outside; white, turning red when cut, (Breitenbach)
Pores: 3-6 per mm, angular or daedaloid, with thick, entire walls that become thin and torn; light buff, (Gilbertson), 1-3 per mm, labyrinthine-porose; whitish, spotted reddish brown when bruised, pores somewhat decurrent onto stem; tube layer 0.2-0.5cm thick, (Breitenbach)
Stem: up to 5cm long, and 1.5cm wide, lateral or central to absent; buff; tomentose, (Gilbertson), 4-7cm x 2-3cm, cylindric-conic, usually with adhering soil, (Breitenbach)
Odor: unpleasant, fungoid, (Breitenbach)
Taste: mild (Breitenbach)
Microscopic: spores 4-6.5 x 3.5-5 microns, broadly elliptic to ovoid, smooth, inamyloid, colorless; basidia 4-spored, 14-17 x 7-7.5 microns, clavate, with basal clamp connection; chlamydospores present in flesh, 5-8.5 microns, nearly round, smooth, colorless; gloeocystidia infrequent to abundant, up to 75 microns long and 7.5-8.5 microns in diameter, highly refractive in Melzer''s reagent, negative in sulfobenzaldehyde, irregular in shape, broadly clavate to cylindric with swellings and constrictions, not incrusted; hyphal system monomitic, generative hyphae with clamp connections, hyphae of upper spongy layer 3-5.5 microns wide, colorless in KOH, "thin-walled, rarely branched", hyphae of lower corky layer "more variable, some thick-walled, with rare clamps, rarely branched", 2.5-4 microns wide, "some thick-walled often branched, with frequent clamps", 2-3 microns wide, "others thin-walled, much branched, with abundant clamps", 2.5-5 microns wide, "tramal hyphae similar to those of lower context", (Gilbertson), spores 4.5-6 x 3.5-4.5 microns, elliptic, smooth, inamyloid, colorless, thin-walled, with droplets; chlamydospores 3-5 x 3-4.5 microns, nearly round, thick-walled, with droplets; gloeocystidia 30-100 x 6-10 microns, cylindric-sinuous to clavate, containing droplets, (Breitenbach)
Spore Deposit: yellowish (Breitenbach), white (Buczacki)
Habitat / Range
typically "on the ground arising from buried roots (perhaps both live and dead roots), also on hardwood and conifer logs, causing a white rot", (Ginns), annual, on numerous hardwood genera, rarely on conifers, often on ground from buried roots; causes white rot of dead hardwoods and white trunkrot of living hardwoods, (Gilbertson), single or in groups, on soil but always associated with buried dead wood, (Breitenbach), summer, fall, (Buczacki)
Similar Species
It differs from similar stemmed polypores in its abundant gloeocystidia and chlamydospores, (Gilbertson). "The presence of both gloeocystidia and chlamydospores distinguishes A. biennis from similar polypores." (Ginns(28) with Latin name italicized)
