Dyer’s Polypore Phaeolus schweinitzii — a root and butt-rot parasite of conifers, prized by fiber dyers
Dyer’s polypore grows at the base of conifers or from their roots, starting as a soft, spongy cushion and expanding into a flat disc or a multi-shelved rosette. Fresh fruitbodies are golden-yellow to orange with a darker brown center; the greenish-yellow pores stain dark brown almost as soon as they’re touched.
It causes a butt rot in living conifers, and few other larger fungi turn up as often or across as much of the region (Mushrooms of Cascadia, Siegel & Schwarz). It is also a favorite of fiber artists for the dye colors it yields.
Find Conifer Stands on Forayz
Dyer’s polypore grows at the base of conifers. Forayz Pro members can browse forest type layers to locate conifer stands; public and private land boundaries are free with any Forayz account.
Identification: Fresh vs. Old
Because the fruitbody persists for months after it stops producing spores, the two photos below of the same species look almost unrelated — color is the biggest clue to how fresh a specimen is.
| Feature | Description |
|---|---|
| Fruitbody | 6–30 (45) cm across. Begins as a lumpy cushion and rounds out into a disc, then either a rosette of several fused shelves or one continuous mass with a dip in the middle. Occasionally grows as a single shelf-like bracket on a log or trunk instead. Dry surface, velvety or hairy at first, growing matted and bumpy with age (Siegel & Schwarz). |
| Color, fresh | Yellow to golden with a pale, whitish or pinkish edge; some specimens run toward neon-orange instead. The cap’s center runs darker than the margin, typically brown to olive-brown, crossed by lighter mustard-toned bands (Siegel & Schwarz). |
| Color, old | Evenly reddish brown to blackish brown. Spent fruitbodies are tough and persistent, and their crumbly, dark remains — described as resembling cow patties — can be found on the forest floor at any time of year (Siegel & Schwarz). |
| Pores | Small, with an angular, often maze-like shape and uneven wall thickness. Muted grayish-olive to dull yellow-green when young, aging to olive-brown; touching or scratching them turns them dark brown to black within moments (Siegel & Schwarz). |
| Stem | Stout but often obscure, irregular and slightly rooting; sometimes off-center or absent (Siegel & Schwarz). |
| Flesh | Spongy and yielding in young specimens, firming up into a tough, fibrous or corky texture as they age (Siegel & Schwarz). |
| Odor / taste | Odor indistinct; taste unpleasant, rancid or sour (Siegel & Schwarz). |
| Chemical test | Cap surface and flesh turn black in KOH (Siegel & Schwarz), sometimes passing briefly through cherry-red first (Arora). |
| Spore print | White, occasionally tinged yellow to green. |
Dark staining, not a fixed color
Color changes a lot as a fruitbody ages, so check the pores as well: they stain dark brown almost as soon as they are scratched (Siegel & Schwarz).
Host & Parasitism
Dyer’s polypore grows singly or in small groups around dying and dead conifers and their stumps, and sometimes directly on trunks or large logs on the ground. It causes a cubical rot in the butt and roots of living conifers, and turns up more often, in more places, than almost any other larger fungus in the region (Siegel & Schwarz). Gilbertson, writing more broadly across North America, names it the major cause of butt rot in Douglas-fir, though it attacks a range of conifer hosts and only rarely hardwoods.
A name in flux
DNA sequencing shows that the PNW fungus long called Phaeolus schweinitzii does not match the European material the name was originally based on, and represents at least two distinct lineages, neither matching European sequences (D. Miller, Danny’s DNA Discoveries). The common one probably now has a name, Phaeolus hispidoides; material from Oregon may belong to a second, still-undescribed species (D. Miller). Field guides and this page still use Phaeolus schweinitzii for the common PNW fungus while that work is finalized.
Similar Species
- Woolly Velvet Polypore (Onnia tomentosa): Also grows at the base of conifers and causes a root rot, but is smaller (4–15 cm), evenly ocher-brown to caramel-tan rather than banded, and its pores don’t stain dark brown when bruised (Siegel & Schwarz). Attacks spruce specifically.
- Onnia subtriquetra: Likewise smaller and more evenly colored than dyer’s polypore, with paler pores that don’t bruise dark brown (Siegel & Schwarz).
Traditional Dye Use
Fresh fruitbodies are prized by fiber artists: paired with an alum mordant they give a bright golden-yellow dye, and with iron a rich olive green (Siegel & Schwarz). Ginns records a wider range of resulting colors — green, yellow, gold, or brown — depending on the material dyed and the mordant used.
Habitat & Season
This page skips a seasonal bar chart. New growth is most abundant from late summer through fall, tapering into occasional fruitbodies over the following weeks of winter (Siegel & Schwarz), but the spent, blackened remains are tough enough to persist on the forest floor for months afterward and turn up in any season. Because iNaturalist observations don’t distinguish a fresh fruitbody from months-old remains, a month-by-month count of sightings mostly tracks when people are out looking, not when the fungus is actually fruiting — so it isn’t a reliable guide to timing here.
Edibility
Not edible
Mushrooms of Cascadia lists its edibility as unknown, and possibly toxic. Arora calls it possibly poisonous, and its taste is unpleasant, rancid or sour (Siegel & Schwarz).
Sources: Mushrooms of Cascadia (Siegel & Schwarz, 2024); MycoMatch (© Ian Gibson), a compilation of published descriptions through which most other field-guide authors named here are quoted; Danny’s DNA Discoveries and the PNW Pictorial Key (© Danny Miller); iNaturalist observations.