Tan Ear Identification Guide

The First Impression

The Tan Ear is a cup fungus that has stopped being a cup. Walking through leaf litter in a damp deciduous or mixed wood in late summer or autumn, you notice what looks like a piece of pale brown leather standing on edge among the leaves — 3–8 cm tall, curled, and split down one side from rim to base so that it stands upright like an ear rather than sitting flat like a saucer.

That asymmetry is the genus character. Most soil-dwelling Pezizales form regular, more or less circular cups; Otidea species are cleft on one flank so that the apothecium is taller than it is wide, often leaning, and frequently a little compressed. There are usually several fruitbodies together, sometimes fused at the base into a small clump, all emerging from the humus layer.

Reading the Outer (Sterile) Surface

Turn one specimen so you can see the outside — the excipulum. In Otidea alutacea it is:

• Pale tan, ochre-buff or greyish-cream, usually a shade paler and duller than the inner face
• Dry and distinctly furfuraceous, meaning finely scurfy or mealy, like fine bran scattered over the surface; a hand lens shows a granular, minutely warted texture
• Without hairs, spines or a gelatinous coat

The margin is usually incurved when young, sometimes minutely toothed or torn, and it may become wavy in age. This scurfy outer surface, matched with the tan tones, is the everyday field separator from smooth-outsided cups.

Reading the Inner (Fertile) Surface

The inner face carries the hymenium, the fertile layer where the asci sit. In this species it is a fairly plain tan, ochre-brown, greyish-tan or clay-brown, matt to slightly waxy in appearance, and even in colour — no pink, no yellow, no apricot flush. Older material darkens somewhat and can look dull olive-brown.

Look for even colour distribution. The most confusable relative shows a distinctly warmer, brighter, sometimes pinkish or apricot inner surface, so a plain, quiet tan is genuinely diagnostic here.

Base, Stem and Flesh

Follow the fruitbody down. It narrows into a short, tapering, stem-like base — not a true stipe, but a compressed extension of the excipulum — that is buried in litter and humus and usually clothed at the very bottom in white mycelial threads binding leaf fragments and soil. Excavating carefully rather than snapping the fruitbody preserves this feature.

Break a piece of the wall. The flesh is thin (about 1–2 mm), pale, brittle and waxy-crumbly, snapping cleanly rather than tearing. It does not exude liquid, does not change colour on exposure, and has no strong odour — mild and slightly earthy at most.

Getting a Spore Deposit

Ascomycetes shed their spores differently from gilled fungi, so the technique needs adjusting. Rather than balancing a cap on paper, place a fresh, mature apothecium fertile-side-up in a closed container over a glass slide or a piece of dark card set a centimetre or two above it, or simply lay the fruitbody hymenium-down against dark card in a humid box. Asci in Pezizales are operculate and discharge actively; a mature specimen brought into a warm room often "puffs", releasing a visible cloud of spores when breathed on or jolted. The deposit is whitish to very pale cream.

Microscopy is where Otidea is settled properly. Mount a razor-thin section of the hymenium in water and look for:

• Asci long and cylindrical, eight-spored, with the spores in a single row, and not turning blue in Melzer's reagent
• Spores ellipsoid, smooth, colourless, roughly 12–16 × 6–8 µm, each typically containing two conspicuous oil droplets (guttules)
• Paraphyses slender, septate, and — the genus signature — curved or hooked at the tips, bending like a shepherd's crook

Smooth, two-guttulate spores plus hooked paraphyses confirm the genus more securely than any macroscopic character.

Substrate and Season

Otidea alutacea is a soil-dwelling species of woodland humus, growing from leaf litter and mull soil rather than from wood, dung or burnt ground. It is found in deciduous and mixed woodland — beech, oak and hazel are frequent overhead — with some records under conifers, and prefers moist, shaded, undisturbed ground on neutral to calcareous soils. Fruitbodies emerge from late summer through autumn, usually in small troops or clustered groups, and often reappear in the same patch of litter in successive years.

Separating the Look-alikes

• Hare's Ear (Otidea onotica) — the commonest confusion. It is generally taller and more elegantly ear-shaped, and the inner surface is a warm ochre-yellow strongly flushed pink, salmon or apricot, quite unlike the plain tan of O. alutacea.
• Toad's Ear (Otidea bufonia) — the same split-ear form, but distinctly dark brown to blackish-brown inside and out.
• Other Otidea species (O. cochleata, O. umbrina and relatives) — a genuinely difficult group; separation depends on shade of brown, degree of clustering, spore dimensions and excipular structure, so microscopy is required for confidence.
• Cups (Peziza spp.) — form regular, unsplit cups sitting flat on the substrate, often fleshier and more brittle, with warted or ornamented spores in many species and asci that frequently turn blue at the tip in Melzer's reagent.
• Elfcups and allies (Tarzetta, Geopyxis) — small, goblet-shaped, with a toothed or crenate margin, and a regular rather than cleft outline.
• Saddles (Helvella spp.) — a true stalked structure with a saddle-shaped or lobed cap, often ribbed and hollow stems, and no cup shape at all.
• Earth Tongues and clubs — upright but solid and club-shaped, never hollow or ear-like.

Field Checklist

Split, ear-shaped apothecium standing upright on woodland soil; plain tan inner face; paler, scurfy outer surface; short tapering base with white mycelium; brittle thin flesh; whitish spore deposit; smooth two-guttulate spores; hooked paraphyses; broadleaf litter in late summer to autumn.