Red-Banded Webcap

Cortinarius armillatus is immediately recognisable - if you look at the stem.

Cap

A fairly ordinary brick-red to chestnut-brown, convex to broadly umbonate, with a dry fibrillose surface that could belong to any number of common webcaps.

Stem

Slide your gaze down the stem and the species announces itself: two, three, or even four vivid orange-red to blood-red concentric rings encircle the stem in the lower half, standing out like painted bracelets against the paler fibrillose background.

These rings are collapsed and stained remnants of the original cobweb cortina - the ephemeral web-like partial veil that connects the cap margin to the stem in young Cortinarius specimens and leaves its mark as spores ripen and stain it rusty-red.

In old specimens the bands may fade or become obscured by soil or weathering; check young, fresh fruit bodies for this feature in its full clarity.

Gills

The gills follow the usual Cortinarius progression: pale clay to cinnamon when young, deepening to a thoroughly rusty cinnamon-brown with spore maturity. The spore print is rusty cinnamon-brown.

Flesh

Firm and pale buff without any colour change on cutting.

The total impression is of a medium to large brown-capped mushroom with a tall, banded stem emerging from moist birch-edge habitat - and those red bands are the character that matters.

Cortinarius armillatus is a birch specialist, and its most reliable habitat clue is often the trees, not the soil.

Look for it at the wet margins of birch woodland:

• where the trees thin out toward bog edges, stream banks, and wet hollows
• where sphagnum or sedge encroaches at the base of the birch trunks
• where the soil is dark, peaty, and stays moist through the summer

In the Pacific Northwest, river birch corridors and wet low-altitude forest edge are the primary search zones.

In Scandinavia and northern Europe it is a classic species of birch carr - that distinctive, rather atmospheric habitat of small birches and mossy tussocks growing in shallow peat.

It does not follow birch into dry, upland settings; the moisture connection is strong and consistent.

Finding this species is a reliable indication of a well-established, mycorrhizally active birch stand with undisturbed soil structure. It will not appear in recently planted birch, disturbed ground, or gardens.

In the Pacific Northwest, C. armillatus fruits from late August through October, with peak abundance in September-October after the first substantial autumn rains break the summer dry period.

The fruiting trigger is the arrival of extended cool and rainy weather, typically when 15-25 mm of rain fall over a 10-14-day period and soil temperatures drop into the 8-14 °C range.

In Scandinavia and the UK, the equivalent window is September-October, tracking the boreal autumn mushroom pulse.

The species is reliably an autumn species and is essentially absent from spring. A good September rain event in established birch bog habitat is the most productive time to search.

As a strict ectomycorrhizal partner of birch, Cortinarius armillatus invests years in building a subsurface mycelial network before fruiting bodies appear.

The underground partnership exchanges photosynthate from the birch for minerals and water from the soil - a genuinely mutual relationship underpinning the nutrition of both partners.

Fruit bodies emerge singly or in small groups of two to five from the soil surface or through moss, never from wood. Because the mycelium is perennial, the same site may produce fruit bodies in multiple consecutive years under suitable autumn conditions.

The mushroom itself - cap, stem, and gills - is only the temporary reproductive structure launched to disperse spores; the organism's centre of gravity is the invisible network below.

Triggered by the first sustained autumn rainfall breaking the summer dry period, combined with soil temperatures cooling below ~14 °C. In the Pacific Northwest, this typically aligns with the September-October rainy season onset. Requires established ectomycorrhizal network in mature birch stands; absent from young or disturbed birch.

The most dangerous confusion scenario involves deadly orellanine-containing webcaps that share birch-edge and mixed-forest habitat in the Pacific Northwest and across the northern range.

• Cortinarius rubellus (deadly webcap) is perhaps the most critical lookalike: orange-red to tawny-brick in the same moist conifer and mixed-forest habitats, with a distinctly acute, pointed umbo, and an ochre-yellow cortina that leaves some banding on the stem - though its bands are typically less vivid, less numerous, and more yellow-orange than the distinctive blood-red rings of C. armillatus. It contains orellanine and is one of the most lethal mushrooms in the temperate world.
• Cortinarius orellanus (fool's webcap) is foxy orange-brown, grows primarily in deciduous oak and birch forest in Europe, has a dry scaly cap, and produces stem girdle remnants in subdued ochre tones - the vivid red bands of C. armillatus are absent, but a hasty glance could create confusion.
• Cortinarius testacea and related cinnamon-brown Telamonia-group webcaps share the same habitat and general appearance but lack the striking red girdle bands; most are undescribed as to precise toxicity and should be avoided.
• Within the Pacific Northwest, various undescribed or incompletely characterised Cortinarius species with brownish caps and banded stems occur; none should be eaten.

The red-banded stem of C. armillatus is genuinely distinctive when the banding is fresh and vivid, but faded or weathered specimens narrow the gap with dangerous relatives.

Moderate-to-high danger from lookalike confusion.

The species itself is not documented as lethally toxic. But its resemblance to confirmed deadly orellanine-containing webcaps in the same habitats, combined with incomplete toxicological characterisation, places any collection in an unacceptably risky category.

The genus-level orellanine risk applies as a precautionary principle.

Any Cortinarius that has been consumed and cannot be identified with 100% expert certainty should be treated as a medical emergency.

Cortinarius armillatus is not collected for food and should not be picked for the table.

It is considered inedible in all standard mycological references due to an unpleasant, bitter or acrid taste, and its full toxicological profile within this notoriously complex genus has not been comprehensively characterised.

More importantly, the red-banded stem - while distinctive - requires careful assessment in the field, and lookalike species in the same habitats include confirmed deadly nephrotoxic webcaps. No forager's basket benefit justifies the risk of error in this genus.

If handling specimens for photographic documentation, use care around the eyes and wash hands after handling. Never place Cortinarius specimens in the same container as edible species.

Cortinarius armillatus has not been confirmed to contain orellanine in peer-reviewed chemical studies, and there is no established record of serious poisoning directly attributed to it.

However, it is consistently classified as inedible in European and North American mycological literature, and the broader genus context demands serious caution.

Cortinarius is the largest genus of agaric fungi and includes some of the most lethal species known to humanity. Orellanine-syndrome mushrooms such as C. rubellus and C. orellanus cause irreversible renal failure with onset delayed by two to three weeks after ingestion.

The difficulty of reliably separating C. armillatus from dangerous congeners in the field - particularly when specimens are old, faded, or freshness is uncertain - means the practical risk is real.

The absence of confirmed toxicity is not the same as confirmed safety; comprehensive toxicological screening across the geographic range of this species has not been done.

Do not eat Cortinarius armillatus.

If any Cortinarius has been eaten by mistake and species identity is uncertain, contact a poisons centre immediately, even if feeling well. Orellanine symptoms can be entirely absent for two to six weeks while renal destruction progresses.

• In North America, call the Poison Control Center: 1-800-222-1222.
• In the UK: 111 or NHS Poisons Information Service.
• In Scandinavia: local poison information centres.