Major Groups > Polypores > Stemmed, Pale-Fleshed


Key to Stemmed, Pale-Fleshed Polypores  

by Michael Kuo

The polypores keyed out below all have stems (lateral or central), and pale flesh (when fresh mushrooms are sliced). Genera included in the key: Abortiporus, Albatrellus, Amylosporus, Bondarzewia, Boletopsis, Grifola, Jahnoporus, Meripilus, Microporellus, Polyporoletus, and Polyporus, as well as a few species from other genera.

1.Growing above ground on the wood of trees, stumps, logs, branches, or sticks.

1.Growing at the very bases of trees or stumps—or growing terrestrially, from buried roots or without clear association with a tree.

2.Stem at maturity black or with a black base (caution: some species develop the black covering slowly, from the base upwards, and may lack the covering when young).

2.Neither stem nor stem base black at maturity.

3.Cap with scales.

3.Cap without scales.

4.Only rarely growing on wood; recorded only from California and the Southwest; scales raised, with sharp edges; stem with white hairs over the blackish portion; mushroom connected through the wood to a large underground mass of tissue (a "sclerotium").
Polyporus tuberaster

4.Always growing on wood; widely distributed but more common east of the Rocky Mountains; scales pressed down, with rounded edges; stem without white hairs; sclerotium absent.

5.Cap dark chestnut brown to reddish brown, often 10 or more cm across.

5.Cap dull yellow to pale tan, rarely wider than 6 cm.

6.Pores hexagonal or angular and radially elongated.

6.Pores round or somewhat angular but not hexagonal, not radially arranged.

7.Mature cap small (under 5 cm across).

7.Mature cap larger than above.

8.Cap brown to golden brown; cap margin hairy; stem usually central.

8.Cap orangish; cap margin not hairy; stem usually lateral, if present.

9.Cap with scales, yellowish to yellowish brown; growing in the Southwest and in California; mushroom connected through the wood to an large underground mass of tissue (a "sclerotium"); basidia without oil droplets.
Polyporus tuberaster

9.Cap smooth, white to creamy, often with a mottled appearance; growing in the tropics or along the Gulf Coast of the United States; sclerotium absent; basidia with oil droplets.

10.Cap dark brown or dark bronze.

10.Cap white, buff, pale brown, or tan.

11.Cap flat or shallowly depressed at maturity, not radially lined; pore surface not running down the stem; widely distributed.

11.Cap vase-shaped by maturity, radially lined; pore surface running down the stem; recorded from the Southeast.
Polyporus virgatus

12.Spores and pore surface amyloid; found from the Southwest to the Gulf Coast and the tropics.
Amylosporus campbellii

12.Spores inamyloid; variously distributed.

13.Mature cap 6–30 cm across; found in northeastern North America.
Polyporus admirabilis

13.Mature cap smaller than above; variously distributed.

14.Growing on the wood of conifers; flesh when dried becoming very hard; spores cylindric with a narrowed end, about 5–6 µm long.

14.Growing on the wood of hardwoods or conifers; flesh not becoming very hard on drying; spores varying.

15.Found in the Southwest; cap creamy becoming brownish, mottled with darker spots.
Polyporus coronadensis

15.Found east of the Rocky Mountains; cap not mottled.

16.With 1–3 pores per mm.
Polyporus craterellus

16.With 6–9 pores per mm.

17.Cap with concentric zones; margin not hairy; widely distributed east of the Rocky Mountains.

17.Cap without concentric zones, margin hairy; recorded from the Gulf Coast and the tropics.
Polyporus tricholoma

18.Fresh cap blue or bluish.

18.Fresh cap otherwise colored.

19.Growing in the Pacific Northwest under Douglas-fir and other conifers; young pore surface whitish, eventually bluish or reddish; clamp connections present.
Albatrellus flettii

19.Growing in northeastern North America under eastern hemlock; young pore surface blue or gray, becoming grayish brown, eventually reddish; clamp connections absent.

20.Mushroom often covered nearly completely with whitish to pinkish pore surface; convoluted, lumpy, and amorphous—or sometimes more or less "normal" looking, with a whitish pore surface that runs down the stem and bruises reddish, and a tan to brown cap; typically growing under hardwoods but occasionally found under conifers; both spores and chlamydospores (roundish, thick-walled, asexual spores) present.

20.Not as above.

21.Mushroom usually consisting of many fan-shaped, petal-shaped, or irregularly shaped caps sharing a stem or arising from a branched stem; occasionally occurring with a single cap.

21.Mushroom usually consisting of one circular, kidney-shaped, or irregularly shaped cap on one stem (though individuals may grow in clusters with stems touching); occasionally with two or more caps ingrown or sharing a stem.

22.Individual caps small (1–4 cm across) when fully grown.

22.Individual caps larger than above when fully grown.

23.Growing under Ponderosa pine, Douglas-fir, and western white pine in western North America; caps yellow to yellowish buff or yellowish brown; flesh brittle.
Albatrellus dispansus

23.Growing at the bases of hardwoods throughout North America; caps grayish brown; flesh not brittle.

24.Growing at the bases of living hardwoods in the southeastern United States and in the Caribbean; caps brownish to pinkish brown; stem lateral; pore surface pinkish buff.
Laetiporus persicinus

24.Not as above.

25.Growing under hardwoods in the southwestern United States; caps yellowish to yellowish brown; mushroom connected to a large underground mass of tissue (a "sclerotium").
Polyporus tuberaster

25.Not as above.

26.Pores averaging 1–2 per mm; cap surface not streaked; spores ornamented.

26.Pores smaller than above (2–5 per mm); cap surface streaked; spores smooth.

27.Found under conifers west of the Rocky Mountains; caps brown to purplish brown.
Bondarzewia occidentalis

27.Found under hardwoods east of the Rocky Mountains; caps whitish to tan or pale brown.

28.Pore surface and cap margin bruising dark brown to black; individual caps to 20 cm across, whitish to brownish; pore surface with 6–8 pores per mm; spores subglobose; clamp connections completely absent.

28.Pore surface and cap margin not bruising; individual caps to 8 cm across, lavender gray becoming brown; pore surface with 2–4 pores per mm; spores ellipsoid; clamp connections present in generative hyphae.

29.Cap usually round in outline, rather than kidney-shaped, lobed or irregular; stem usually more or less central; multi-capped or fused mushrooms rare.

29.Cap occasionally round in outline but usually "roundish" to kidney-shaped, irregular or lobed; stem central or off-center; multi-capped or fused mushrooms more likely than above.

30.Stem terminating in a long, underground root-like projection.

30.Stem without a root-like projection.

31.Above-ground portion of stem black and velvety.
Polyporus melanopus

31.Above-ground portion of stem whitish to reddish brown, not velvety.

32.Flesh in cap fairly thick, staining grayish, pinkish, or brownish when sliced; spores nodulose.

32.Flesh in cap thin, not staining when sliced; spores not nodulose.

33.Cap dull orange with gray areas; rare; found in the Pacific Northwest.
Boletopsis smithii

33.Cap grayish to brownish; variously distributed.

34.Growing under pines; cap pale gray; mushroom usually short, with the cap about as wide as the stem is long.
Boletopsis grisea

34.Growing under spruces; cap dark gray; mushroom usually tall, with the stem longer than the cap width.

35.Growing in open fields, grassy areas, etc.; cap small (up to 3 cm across), grayish.
Polyporus cryptopus

35.Not as above.

36.Growing under hardwoods.

36.Growing under conifers.

37.Cap brownish to yellowish, with olive to greenish shades; pore surface with greenish or olive shades.

37.Not as above.

38.Pores large (1–2 per mm).

38.Pores small (4–10 per mm).

39.Cap whitish to pale yellowish or pale brownish, surface with small brownish scales; pore surface whitish; flesh white; arising from a large underground mass of tissue (a "sclerotium").
Polyporus tuberaster

39.Cap dark purplish gray, cinnamon buff, or tawny, surface hairy or velvety; pore surface grayish to purplish gray or olive; flesh pinkish; sclerotium absent.
Polyporoletus sublividus

40.Cap usually with concentric zones; pores very tiny (8–10 per mm); found in the southeastern United States.

40.Cap not strongly zoned; pores 4–6 per mm; variously distributed east of the Rocky Mountains.

41.Cap yellow to yellow-brown; margin usually inrolled when young; stem yellowish or buff; spores elliptical.
Albatrellus peckianus

41.Cap white, becoming straw-colored with age; margin not typically inrolled; stem white; spores nearly round.
Abortiporus fractipes

42.Cap scaly, with yellowish green shades; pore surface whitish, bruising and aging yellowish green or greenish; stem with yellowish green shades.
Albatrellus ellisii

42.Not completely as above.

43.Stem brown and minutely velvety; spores 12–17 µm long, spindle-shaped.
Jahnoporus hirtus

43.Stem paler than above, smooth; spores smaller, not spindle-shaped.

44.Cap smooth when young (though possibly becoming cracked by maturity), creamy to whitish (but not orangish or pinkish buff); clamp connections absent.

44.Young cap smooth or scaly, more highly colored (grayish to brownish or pinkish buff); clamp connections present.

45.Cap cracking with age and showing pale yellowish flesh in the cracks; fresh stem and pore surface without reddish or orangish shades; spores inamyloid; widely distributed.

45.Cap rarely cracking with age, and then not showing flesh in the cracks; fresh stem and spore surface sometimes with reddish or orangish shades; spores amyloid; apparently southern (FL & AZ) in distribution.
Albatrellus subrubescens

46.Cap grayish becoming grayish brown, not cracking; stem reticulate, with greenish to brownish blotches; pore surface yellow; spores 7.5–10 x 5–7 µm; rare (apparently documented only once, in Washington).
Albatrellus skamanius

46.Not as above.

47.Cap brown, with small scales; pores large (1–2 per mm or larger) and hexagonal or angular; stem bruising and discoloring brown to reddish brown.

47.Cap orangish to pinkish buff, smooth; pores small (3–5 per mm) and circular; stem not discoloring brownish.

This site contains no information about the edibility or toxicity of mushrooms.

Cite this page as:

Kuo, M. (2007, April). Key to stemmed, pale-fleshed polypores. Retrieved from the MushroomExpert.Com Web site:

© MushroomExpert.Com