Tear Dropper Identification Guide

The First Impression

Finding the Tear Dropper is a matter of turning things over. It does not stand up, it has no cap and no stipe, and nothing about it will catch your eye from a standing position. The setting is the shaded interior of a conifer wood — spruce, pine, larch or fir — where fallen branches and barkless trunk sections have lain long enough to go grey and hard. Roll a dead branch out of the moss, look at the underside, and you may find a thin pale crust spread flat over the wood like a layer of dried paint that someone has stippled with a coarse brush.

That flat, wood-hugging habit is the starting point. Crust fungi are read in a completely different order from gilled mushrooms: outline and margin first, then the texture of the fertile surface, then the way the whole sheet behaves when you press and cut it.

Reading the Growth Form

The fruitbody is resupinate, meaning it is laid down face-up on the substrate with no separate cap of any kind. It begins as small discrete patches a few millimetres across and spreads by fusing with its neighbours, so a well-developed colony can be an irregular sheet ten or twenty centimetres long, following the contours of the wood, running into cracks and occasionally lipping over an edge.

Colour is pale and unassuming: white or cream when young and actively growing, ageing through pale ochre and buff to a dull greyish-tan or dirty straw. It does not have the bright yellows or oranges of some crusts, nor the pinkish or violet tones of others. Against pale weathered conifer wood it is genuinely easy to overlook.

The margin is worth a lens. In active material it is thinning, paler, and finely fringed or fibrillose, sometimes with visible white mycelial threads spidering out onto the bare wood ahead of the sheet. Older, dried colonies often lose that fringe and instead crack away from the edge.

Reading the Fertile Surface

Now the diagnostic feature. The spore-bearing surface is not smooth, not poroid and not gilled — it is odontioid, covered in short, blunt to conical spines or tubercles, each typically well under a millimetre to a couple of millimetres long. They stand more or less perpendicular to the wood, are usually crowded but irregular in spacing and length, and give the surface a rasp-like or granular feel under a fingertip.

The second diagnostic feature is the one the common name records. When the fungus is growing actively in humid conditions, clear watery droplets are exuded from between and on top of the spines, beading up like sweat on the crust. A colony caught in this state, glistening with droplets, is unmistakable in the field, though the droplets vanish as soon as conditions dry and you cannot count on seeing them.

As the crust ages and dries it hardens noticeably and the surface cracks into small angular plates, with the fissures running between groups of spines. A very old colony can look like a crazed ceramic glaze studded with worn stubs.

Texture, Flesh and Section

Press the crust with a thumbnail. Fresh material is waxy to cartilaginous and firmly attached to the wood; you cannot peel it off in one piece as you can with some crusts, and it tends to flake away instead. Dried material is hard and brittle.

Cut a section perpendicular to the surface with a razor blade and look at the cut edge with a lens. The tissue layer is thin — often less than a millimetre thick apart from the spines — pale and homogeneous, with no visible layering into distinct zones. There is no colour change on cutting or bruising, no latex, and no obvious smell. This absence of reactions is itself informative: a number of similar crusts stain, bleed or smell strongly.

Taking a Spore Print

You cannot balance a crust fungus gills-down on paper, so the technique changes. Cut a small chip of wood carrying an actively growing patch, and suspend or prop it face-down a few millimetres above a glass slide or a piece of black card inside a covered container to keep the humidity up. Left overnight, a productive colony will drop a faint whitish deposit — often so sparse that you only see it by tilting the slide against the light.

Under the microscope the spores are the confirmation: small, hyaline, smooth, thin-walled, and distinctly allantoid, which is to say curved like a tiny sausage or a comma rather than ellipsoid or round. Alongside them you should find slender, thin-walled hyphae with clamp connections at the septa, and — the detail worth hunting for — projecting cystidia whose tips are heavily encrusted with coarse crystalline granules. That combination of allantoid spores, clamped hyphae and crystal-encrusted cystidia arising in a spiny, drop-exuding crust on conifer wood is what pins the identification down.

Substrate and Season

This is a wood-rotting saprotroph with a clear preference for conifer timber, most often the underside of fallen branches, decorticated logs and old stumps in shaded, humid situations; hardwood records exist but are much less usual. It favours wood that has already lost its bark and progressed some way into decay, and it is a species of continuous woodland rather than isolated garden timber.

Crust fungi are far less seasonal than agarics. Fruitbodies are perennial in effect, persisting on the wood through the year and reviving to produce spores whenever conditions are wet enough, so the crust can be found in any month. The droplet-exuding phase, however, is tied to sustained damp weather, and autumn and mild wet winter spells give the best chance of seeing it.

Separating It From Look-alikes

Spiny white and cream crusts are a crowded field, and honest identification here is a two-stage process: narrow it in the field, confirm with a lens or microscope.

Its closest relative is a similar conifer crust that is more tuberculate than spiny, tending toward low warts rather than well-formed teeth, usually greyer and more strongly cracked, and lacking the conspicuous exuded droplets.

The Mycoacia-type crusts on hardwood have longer, finer, more evenly cylindrical spines and are frequently tinged yellow or ochre-yellow throughout. The toothed Steccherinum crusts are pinkish, salmon or rusty-orange rather than white-cream and often develop a small reflexed bracket edge. Radulomyces crusts have coarser, blunter, more scattered warts on a distinctly waxy, sometimes translucent surface and are usually on hardwood. The various Xylodon and related crusts can look extremely similar in the field but differ in spore shape — ellipsoid rather than allantoid — which the print resolves.

Finally, do not confuse a genuine spiny crust with the pored underside of a resupinate bracket: run a lens along the surface and confirm that the projections are solid free-standing teeth, not the raised walls of tubes.