Trichaptum abietinum
Description
This attractive small, leathery shelf fungus makes up in numbers for its lack of size, often dominating on conifer logs. The white, hairy, zonate cap, usually with a purplish margin when young, and purple-tinged pores make it easy to recognize, although in age the pores may breakdown to form spines causing possible confusion with species of tooth fungi. The gorgeous, purple-when-fresh pore surface.
Look-alikes include Schizophyllum commune, also with a whitish, hairy cap, distinguished by a "split gill" hymenium, and Fomitopsis cajanderi, an uncommon but larger, woody polypore that has a blackish-brown cap and pinkish pore surface. A closely related species, Trichaptum biformis, (aka Hirschioporus pargamenus), grows primarily on hardwoods.
When tinged with purple, the pore surface of this smallish but gregarious annual bracket fungus is very distinctive; however, sometimes the pore surface is brown with hardly a hint of purple. The variable shape - sometimes resupinate but more often sharply reflexed (bracket like) can cause confusion too.
Mushroom Identification
Ecology
Saprobic on the dead or dying sapwood of conifers, especially firs; growing in overlapping clusters on logs and stumps; spring through fall; widely distributed in North America.
Cap
Sometimes absent, or present as merely a folded-over edge, but usually present and semicircular to fan-shaped; 1–4 cm wide; up to 3 cm deep; thin; dry; fuzzy to hairy; with concentric zones of texture and color; shades of gray, with a purplish marginal zone when fresh; often hosting algae and becoming green.
Pore Surface
Purple when fresh, especially near the margin; fading to lilac or brownish with age; with 2–3 angular pores per mm; often tooth-like with age or in capless areas; not bruising.
Flesh
Whitish; tough and leathery.
Microscopic Features
Spores 6–8 x 2–3 µm; smooth; cylindric to slightly allantoid; hyaline in KOH; inamyloid. Cystidia abundant; 20–30 x 5–10 µm; clavate to obutriform; smooth overall but developing distinctive crystalized apices; walls 0.5 µm thick; hyaline in KOH. Hyphal system dimitic; skeletal hyphae 4-9 µ wide, thick-walled, unclamped; generative hyphae 2.5–5 µm wide, thin-walled, clamped.
History
The basionym of this polypore dates from 1793, when it was described scientifically by British naturalist Dickson, who gave it the binomial scientific name
The currently-accepted scientific name Trichaptum abietinum dates from a 1972 publication by the Norwegian mycologist Leif Randulff Ryvarden (b. 1935).
Synonyms of Trichaptum abietinum include Boletus abietinus Dicks., Polyporus abietinus (Dicks.) Fr., Polystictus abietinus (Dicks.) Cooke, Hirschioporus abietinus (Dicks.) Donk, and Trametes abietina (Dicks.) Pilát.
Purplepore Bracket growing on a long-dead pine log, top view (southern England)
The generic name Trichaptum means 'with clinging hairs', and the specific epithet abietinum means 'inhabiting fir trees' (trees of the Abies genus), although this wood-rotting bracket will also attack other kinds of conifers and, very occasionally, some hardwoods too.
Photo sources:
Photo 1 - Author: Dario (Public Domain)
Photo 2 - Author: Dario (Public Domain)
Photo 3 - Author: Keith Seifert (CC BY-SA 4.0)
Photo 4 - Author: Michel Langeveld (CC BY-SA 4.0)
