Cortinarius orellanus Identification Guide

Where You Are Standing When You Find It

Almost every encounter with Cortinarius orellanus begins in open, warm broadleaf woodland on poor acidic ground: scattered oaks above bracken and bilberry, birch along a sandy heath edge, or thin beech on a well-drained slope. It is a mycorrhizal partner of trees, so it pushes up through bare soil and leaf litter and never grows out of wood. It also prefers the lighter, drier parts of a wood rather than deep sodden shade. Fruiting bodies come up singly or in loose scattered troops of three or four rather than in tight clusters, and they are middle-sized. From standing height what you notice is a dry, matt, foxy-orange disc a few centimetres across sitting just clear of the litter. Nothing about it glistens and nothing about it is pale. The whole fungus reads as one warm rusty colour from the cap right down to the stipe base, and that overall monochrome tawny impression is the first thing to register before you touch it.

Reading the Cap

The cap is 3 to 8 centimetres across, occasionally a little more. It begins convex and bun-shaped, then flattens out to a broadly umbonate disc with a low, wide, rounded rise in the middle rather than a sharp point. The margin is inrolled when young, becoming level and often slightly wavy or lobed in age, and on very young caps you may see fine pale veil threads hanging from it. Run a finger over the surface: it is dry in all weathers, never sticky, never greasy, even after rain. Under a hand lens the surface is finely fibrillose and breaks into small flat innate scales towards the centre, giving a suede or fine felt texture. Colour is tawny orange to rusty red-brown, remarkably uniform, sometimes a shade paler at the very edge. Importantly it is not strongly hygrophanous, so you do not get the two-tone drying bands that many brown woodland agarics show.

The Spore-Bearing Surface

Turn the cap over and the gills give you the second strong character. They are adnate to sinuate, notched where they meet the stipe, quite thick, deep from edge to attachment, and conspicuously widely spaced. You can count them without difficulty and see litter through the gaps. Young gills are dull ochre, saffron or pale cinnamon. As spores mature and accumulate the whole surface deepens to a rich rusty cinnamon-brown. Gill edges are even to very slightly uneven and concolorous with the faces, with no contrasting pale fringe. There is no membranous covering over the young gills. Instead, a pale cobwebby veil of fine silky threads, the cortina that gives the genus its name, spans from cap margin to stipe. It collapses as the cap expands and leaves no proper ring, only a faint fibrillose zone on the stipe that turns rust-coloured as falling spores lodge in it. Finding those rusty fibrils under a lens is a reliable genus-level confirmation.

Stipe, Base and Flesh

The stipe is 4 to 9 centimetres long and 1 to 2 centimetres thick, roughly cylindrical, tapering gradually downwards to a narrowed or bluntly pointed base. It is solid and firm rather than hollow. Colour is pale to bright yellow-ochre with a silky longitudinal sheen, usually noticeably paler and yellower than the cap. Critically for this species the stipe is essentially unbanded: it may carry vague paler yellowish fibrillose smears, but not the crisp, contrasting girdles seen in some relatives. There is no volva, no marginate bulb and no rim at the base, which is simply narrowed and bound into the litter by yellowish mycelial threads. Split a whole fruiting body lengthwise with a knife. The flesh is yellowish to pale ochre throughout, a little firmer in the stipe, and does not change colour dramatically on exposure. Handled or bruised surfaces may darken slowly to rust-brown over hours, but there is no blueing, no reddening and no instant reaction. The smell is faint, slightly earthy or radish-like.

Taking and Reading a Spore Print

A print is not optional here, because it places the fungus in the right family immediately. Choose a mature cap that is fully expanded but not collapsing, cut the stipe off flush, and set the cap gills-down on a sheet of paper that is half white and half black, or on aluminium foil. Cover it with a bowl or cup to hold humidity and still the air, and leave it four to twelve hours at room temperature. The result should be a thick, unmistakable rust-brown to cinnamon-ochre deposit. That single observation removes every white-spored, pink-spored and black-spored genus from consideration. Under a microscope the spores measure roughly 8.5 to 12 by 5.5 to 7.5 micrometres, are ellipsoid to almond-shaped and coarsely warted, and turn reddish-brown in Melzer reagent.

Substrate and Season

This is an ectomycorrhizal species of broadleaved trees, principally oak, beech and birch, with records under sweet chestnut and hornbeam, on sandy, gravelly or otherwise acidic and free-draining soil. It fruits from late summer through mid autumn. It is chiefly a warm-temperate species, common in central and southern Europe and thinning out markedly towards the north. Two ecological facts do most of the work in identification: it grows from soil, never from wood, and it is a broadleaf associate, not a conifer one.

Separating the Closest Look-alikes

Cortinarius rubellus is the most important comparison. It grows in mossy conifer forest, is taller and more slender in proportion, has a sharply conical or distinctly pointed umbo rather than a low broad one, and carries clear yellow to ochre fibrillose belts around the stipe. Set the two side by side and the banded, spindly, pointed C. rubellus contrasts strongly with the stout, smooth-stiped, blunt-umbonate C. orellanus.

Cortinarius cinnamomeus and C. croceus are much smaller and thinner, with darker olive-brown caps, thin yellow stipes and gills that are bright saffron-yellow or brick-orange rather than tawny, usually in damp mossy ground.

Cortinarius bolaris has a pale cream ground colour overlaid with distinct blood-red scaly patches, a completely different visual pattern, and C. malicorius pairs an olive-brown cap with vivid orange-red gills under conifers.

Gymnopilus species such as G. penetrans also drop rusty spores, but they grow on wood, stumps, buried timber or conifer needle mats, are brighter yellow, and their gills become rust-spotted rather than uniformly cinnamon.

Inocybe and Hebeloma species drop dull snuff-brown or clay-brown prints, not bright rust, and are respectively strongly radially fibrillose with a conical cap, or smooth and sticky with a pale cap.

Chanterelles are sometimes confused at a glance because of colour, but they have blunt, forked, decurrent ridges instead of true blades, no cortina, and a pale spore print.

Field Checklist

• Dry, matt, finely scaly, uniformly foxy-orange cap with a low broad umbo
• Thick, widely spaced gills turning rusty cinnamon
• Cobwebby cortina leaving a rust-dusted fibrillose zone, never a true ring
• Yellow-ochre stipe, tapering downwards, without sharp girdles or a bulb
• Yellowish unchanging flesh
• Rust-brown spore print
• Soil under oak, beech or birch on acid ground, late summer to autumn