Major Groups > Polypores > Stemmed, Pale-Fleshed > Abortiporus biennis


Abortiporus biennis

[ Basidiomycetes > Polyporales > Meripilaceae > Abortiporus . . . ]

by Michael Kuo

As I have collected it, Abortiporus biennis is usually a true oddball--a gnarled, messy-looking mass of irregular white pores that exude a reddish juice and bruise reddish brown. There is hardly a cap or a stem to speak of, and as it grows it engulfs sticks and blades of grass the way some species of Hydnellum do. This gnarled form of Abortiporus biennis, sometimes given the separate species name of "Abortiporus distortus," is apparently the most commonly encountered form of the species, though it does have a more normal looking form with an identifiable cap and stem (see the illustrations).

Though Abortiporus biennis is easily recognized without recourse to a microscope, its microscopic features are distinctive and interesting--from its cystidia to the presence of both spores and chlamydospores (roundish, thick-walled, asexual spores).


Ecology: Saprobic on the wood of hardwoods and occasionally conifers; growing alone or gregariously around the bases of stumps and living trees; causing a white rot in deadwood and a white trunk rot in living wood; summer and fall (winter and spring in warm coastal areas); widely distributed in North America.

Cap: Often covered with the pore surface, but when definable up to 20 cm across; kidney-shaped to semicircular or irregular in outline; whitish to pale brown or reddish brown; sometimes with concentric zones; finely velvety or fairly smooth.

Pore Surface: Whitish, bruising and discoloring reddish or pinkish brown; pores angular to maze-like or irregular, 1-4 per mm; tubes to 6 mm deep.

Stem: Often absent or poorly defined, but when present up to 6 cm long; whitish; velvety.

Flesh: White to pinkish or pale tan; exuding a pinkish juice when squeezed; 2-layered in mature specimens; tough.

Chemical Reactions: KOH negative on flesh.

Spore Print: White.

Microscopic Features: Spores 5-8 x 3-5 µ; smooth; broadly elliptical; inamyloid. Chlamydospores round or nearly so; 5-9 µ. Gloeocystidia infrequent to numerous; variously shaped; up to 75 µ long.

Heteroporus biennis is a synonym, as is Abortiporus distortus (see discussion above).

REFERENCES: (Bulliard, 1798) Singer, 1944. (Fries, 1821; Saccardo, 1888; Overholts, 1953; Arora, 1986; Gilbertson & Ryvarden, 1986; McNeil, 2006; Binion et al., 2008.) Herb. Kuo 06110301, 07160404, 09180405, 10240402, 10240703.

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Abortiporus biennis

Abortiporus biennis

Abortiporus biennis

Abortiporus biennis

Abortiporus biennis

Abortiporus biennis

Abortiporus biennis

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Kuo, M. (2004, November). Abortiporus biennis. Retrieved from the MushroomExpert.Com Web site: