Palamino Cup Identification Guide

First Impressions and the Setting

You are picking your way along a damp woodland path in spring or early summer, past a pile of hardwood chips at a trail junction or a soft, half-buried beech log. Sitting on the wood are several pale tan discs, cupped like shallow saucers, one or two the size of a coffee-cup rim and a few smaller. From above they look like shed bark or a scattering of wet leaves; only when you crouch does the shape resolve into a proper cup with an upturned, slightly wavy rim. Palamino Cup usually grows gregariously, sometimes crowded enough that neighbouring cups press against one another and go lopsided, and it is nearly always attached to wood or wood debris rather than sitting on bare soil.

Reading the Cup

Fruitbodies are 3-10 cm across, occasionally larger. They start as small closed or nearly closed cups and expand steadily, first into a deep bowl, then a shallow saucer, and finally into a flattened, undulating disc whose margin turns up, becomes irregularly wavy and characteristically splits into a few radial tears. Old specimens can look like a crumpled pancake. Note that expansion, because the name refers to this repand, spreading habit and it is one of the more reliable gross characters in a genus where colour is unhelpful.

The Spore-Bearing Surface

The inner face of the cup is the hymenium - the fertile surface where the spore-shooting asci sit - and in this species it is smooth, matte to very slightly shining, and pale tan, yellowish-brown, buff or light brown, sometimes with a faint pinkish or greyish cast in wet weather. It should not be strongly wrinkled, ribbed or veined. Colour deepens somewhat with age and drying. Look at it under a lens in good light: the surface is even and uninterrupted, with no folds and no hairs.

The Outer Surface and Margin

Turn a cup over, which is where much of the identification lives. The outer surface is distinctly paler than the inside - whitish, cream or pale buff - and it is minutely scurfy, mealy or bran-like, as if lightly dusted with flour or fine granules. Under a lens that texture resolves into small scattered granular tufts. Critically, the outside is not hairy: there are no brown bristles or shaggy hairs, which rules out several other cup-fungus groups at once. The margin is thin and often slightly paler still, and in fully expanded specimens it is torn and turned back.

Stalk, Base and Attachment

There is essentially no stalk. The cup narrows to a small central point of attachment, sometimes a very short stalk-like base a few millimetres long, and that base is fixed directly to wood - a rotting log, a stump, sawdust, wood chips, or a buried branch beneath what appears to be bare ground. When a specimen seems to be growing from soil, scrape the surface: you will usually find a piece of wood underneath. Confirming the woody substrate is a real identification step, not an afterthought.

Flesh and Colour Change

Take a cup between finger and thumb and bend it. The flesh is thin - a millimetre or two - brittle and slightly waxy, and it snaps cleanly with a crisp break rather than tearing like leather or squashing like rubber. In section it is whitish to very pale tan and has no distinct layering visible to the eye. There is no latex, no bruising reaction and no colour change on cutting; the flesh looks the same after five minutes as it did on cutting.

Getting Spores and Reading Them

Cup fungi do not print in quite the same way as gilled mushrooms, but they can be persuaded. The simplest method is to rest a mature cup hymenium-side down over a sheet of white paper or a glass slide, cover it, and leave it a few hours in a still place; a fine whitish deposit accumulates beneath. There is a second, more entertaining route that also confirms the group: bring a fresh cup into warm air, breathe on the inner surface or leave it in sunlight for a minute, and a visible puff of spores is released in a small cloud, sometimes with a faint hiss, as thousands of asci discharge together. Under a microscope the spores are smooth, colourless and elliptical, roughly 14-17 by 8-11 micrometres, arranged in a single row of eight inside a long cylindrical ascus, and the ascus tip stains blue in iodine solutions - the standard confirmation that you are in the operculate cup fungi rather than among the jelly fungi or the true agarics.

Substrate, Season and Ecology

Palamino Cup is a saprotroph that decomposes broadleaf wood and woody debris. Typical stations are rotting logs and stumps, sawdust heaps, landscaping wood chips, mulched beds, damp cellars and greenhouses, and disturbed ground where wood has been buried. It has no tree partner. Fruiting is favoured by cool, wet conditions and by freshly disturbed wood, so mulched garden beds often produce a flush a few weeks after the mulch is laid; the main season is spring through early summer, with a secondary appearance in autumn. Individual cups mature and collapse quickly, so a colony changes composition every few days.

Separating the Look-alikes on Morphology Alone

• Peziza varia: very close and genuinely hard to separate on gross features. It also grows on wood and has a similar pale brown cup, but it tends to have a thinner, more delicate and more strongly veined-looking cup with a less pronounced scurfy exterior; reliable separation is microscopic.
• Peziza badia: dark reddish-brown to olive-brown inside, growing on soil rather than wood, and its spores are conspicuously warted and net-marked under the microscope.
• Peziza vesiculosa: grows on dung, manured straw and compost, keeps a strongly inrolled margin, has a blistered, uneven inner surface, and is thicker and more persistent.
• Peziza domiciliana: appears indoors on plaster, damp masonry and behind pipes; it is whiter to pale grey and often develops a longer stalk-like base.
• Gyromitra ancilis and relatives: larger, thicker and more leathery, brownish, usually on conifer wood, with a ribbed or veined outer surface and a lumpy underside.
• Tarzetta and Humaria species: much smaller. Tarzetta cups keep a deep, goblet shape with a distinctly toothed or notched margin and a stalk; Humaria hemisphaerica is white inside with a coat of stiff brown hairs outside, quite unlike the smooth scurfy exterior here.
• Aleuria aurantia: bright orange inside, whitish and downy outside, growing on bare disturbed soil and gravel rather than wood.

Working Checklist

Large pale tan cup expanding to a flattened, wavy, split disc; smooth pale brown inner surface; paler minutely scurfy but hairless outer surface; no real stalk; thin brittle waxy flesh; whitish spore deposit and a visible spore puff; growing on rotting hardwood, sawdust or wood chips in spring and early summer.