Major Groups > Polypores > Hapalopilus croceus


Hapalopilus croceus

[ Basidiomycota > Polyporales > Phanerochaetaceae > Hapalopilus . . . ]

by Michael Kuo

Here is a medium-sized, orange polypore found on oaks in eastern North America. Its upper surface is finely fuzzy, and its undersurface features angular orange pores. It might be confused with Laetiporus sulphureus, but the latter species grows in shelving clusters and features a yellow pore surface.

Hapalopilus croceus is one of only a few species in the genus Hapalopilus, which was traditionally defined on the basis of microscopic features (including a monomitic hyphal system with clamp connections) and the dramatic red and purple reactions of the mushrooms when a drop of KOH is applied. However, a recent study (Justo and collaborators 2017) has placed Hapalopilus smack-dab in the middle of some unexpected bedfellows, and the future of the genus as traditionally defined is uncertain.


Ecology: Saprobic and parasitic on the wood of oaks; growing alone or in small groups; causing a white rot of the heartwood; summer and fall; widely distributed east of the Great Plains. The illustrated and described collection is from Ohio.

Cap: 4–10 cm across; 3–5 cm deep; semicircular to kidney-shaped; convex; moist; finely fuzzy; golden orange.

Pore Surface: Bright golden orange; not bruising; with 2–3 angular pores per mm; tubes to 2–4 mm deep.

Stem: Absent.

Flesh: Thick; zoned with zones of golden orange, pastel orange, and brownish; fairly soft.

Chemical Reactions: KOH instantly dark purple on all parts.

Microscopic Features: Spores 7–8 x 4–5 µm; ellipsoid; smooth; hyaline in KOH; inamyloid. Hyphal system monomitic; hyphae 2–4 µm wide, smooth or encrusted, hyaline or brownish orange, thin-walled, septate, clamped at septa, often agglutinated with brownish to orangish encrusting material.

REFERENCES: (Persoon, 1796) Bondartsev & Singer, 1941. (Overholts, 1953; Gilbertson & Ryvarden, 1986; Justo et al., 2017.) Herb. Kuo 07151604.

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Hapalopilus croceus

Hapalopilus croceus

Hapalopilus croceus

Hapalopilus croceus

Hapalopilus croceus

Hapalopilus croceus

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Kuo, M. (2018, November). Hapalopilus croceus. Retrieved from the MushroomExpert.Com Web site: