Abortiporus biennis: The Ultimate Mushroom Guide

About The Abortiporus biennis Mushroom

Abortiporus biennis feeds on buried wood (roots, stumps) of dead trees and occasionally of conifers. It can also parasitize the roots of living trees. It eventually can develop a more typical-appearing rosette of caps and stems, but initially takes on several lumpy forms. It should ooze red droplets when the flesh is squeezed.

This wood-rotting fungus sometimes forms very attractive rosettes - and some people refer to it as the Blushing Rosette - but more often it grows as an amorphous mass of irregular maze-like pores exuding blobs of red-brown juice that eventually dry to leave brown stains of the pore surface.

This mushroom occurs throughout Britain and Ireland as well as in many parts of mainland Europe and North America.

Other names: Bleeding or Blushing Rosette.

Abortiporus biennis Identification

1. 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 (also winter and spring in warm climates); widely distributed in North America.

2. "Aborted" Form

   An irregular mass of exposed pore surface, with or without a clearly defined upper surface that is smooth and reddish-brown; ranging from singular and vaguely cup-shaped to clustered or nearly coral-like, with separated, individual projections; pore surface whitish to pinkish, bruising reddish to reddish-brown; pores angular to maze-like or irregular, 1–3 per mm; flesh tough, whitish to pinkish, when fresh exuding a pinkish to orangish liquid.

3. Cap

   5–15 cm across; roundish-to semicircular, kidney-shaped, or irregular in outline; plano-convex; finely to thickly velvety, or sometimes more or less bald; dry; light brown to reddish-brown or tan, with a pale margin; sometimes with concentric zones of brown shades.

4. Pore Surface

   Whitish, bruising and discoloring reddish or pinkish brown; pores appearing "stuffed" when young, later angular to maze-like or irregular, 1–4 per mm; tubes to 5 mm deep.

5. Stem

   When present 3–10 cm long; 1–3 cm thick; lateral; tapering to base; soft and spongy; fuzzy; brownish.

6. Flesh

   White to pinkish or pale tan; exuding a pinkish juice when squeezed; tough.

7. Spore Print: White.

Abortiporus biennis Taxonomy & Etymology

In 1789, when French mycologist Jean Baptiste Francois Pierre Bulliard described this species, he gave it the binomial scientific name Boletus biennis. The currently-accepted name Abortiporus biennis dates from a 1944 publication by German-American mycologist Rolf Singer.

Synonyms of Abortiporus biennis include Boletus biennis Bull., Sistotrema bienne (Bull.) Pers., Hydnum bienne (Bull.) Lam. & DC., Daedalea biennis (Bull.) Fr., Polyporus biennis (Bull.) Fr., and Phaeolus biennis (Bull.) Pilát.

Abortiporus biennis is the type species of the genus Abortiporus, which contains just three species.

Abortiporus, the genus name, comes from the Latin Abortus- meaning arrested development (of an organism), and -porus, derived from ancient Greek and meaning a pore. The specific epithet biennis means biennial (although the fruitbodies of this fungus are annual!)