Lace Lichen Identification Guide

The First Impression And The Setting

Lace Lichen announces itself from a distance in a way that almost no other lichen does. Drive a coast road in the fog belt on a grey morning and the oaks look as though they have been draped in torn grey-green curtains, some strands hanging a hand's length, others reaching well past a metre. Where the drapery is heavy it moves in the wind as a single soft mass, and the tree beneath is half hidden.

The setting is the diagnosis half-made. Ramalina menziesii is a creature of the Pacific fog belt, running from the coastal ranges of Alaska and British Columbia south through Oregon and California to Baja California, and it thrives exactly where summer fog rolls inland at night and drips off the canopy at dawn. Move ten miles inland out of the fog and it thins to nothing. Its favoured supports are oaks — coast live oak and valley oak above all — with bay laurel, willow, alder and even fence wire and old pines used freely. It grows on outer branches with good air movement, and it is most luxuriant on the fog-facing side of a tree.

Everything else is confirmation, and confirmation begins with a single strand held up to the light.

Reading The Thallus: The Net Is Everything

Take one strand, ideally a fallen piece from the ground rather than a piece pulled from a branch. Lay it on a dark surface or hold it against the sky.

The thallus is fruticose, meaning it is a free-hanging three-dimensional body rather than a crust or a flat leafy sheet. It descends in flattened, strap-shaped branches, and the surface of those straps is perforated. This is the character to fix on: the perforations are not tears or damage, they are structural openings that repeat regularly, turning each strap into a net of narrow interlacing strands with elongated diamond or oval holes between them. Some parts of a thallus stay solid and strap-like; the mature reaches become an open reticulate lace, which is where the name comes from.

Look at the mesh with a hand lens. The strands bounding each hole are smooth-edged and continuous, and the net widens as it descends, so a strand is typically narrow and unperforated near the point of attachment and increasingly open toward its tip. Colour is a pale greenish grey, greener when wet, greyer and slightly chalky when dry. Wet a dry piece with a drop of water and it visibly greens within seconds as the algal layer rehydrates — a satisfying demonstration and a useful reminder that this is a partnership between a fungus and a green alga rather than a plant.

Feel the texture. Dry, the thallus is stiff, brittle and crackles slightly; wet, it is soft, leathery and pliable. This dramatic change in handling is normal and is worth testing before deciding a specimen is too fragile to be the right species.

The Holdfast And Branching

Trace a strand up to where it meets the bark. There should be a single, small, tough holdfast — a compact attachment point rather than a spreading crust, and without any root-like rhizines on the underside. From that holdfast the thallus branches repeatedly, generally in a flattened plane, so the whole body reads as a hanging tassel rather than a bushy tuft.

Now test the anatomy. Take a strap and pull it apart slowly along its length. It should tear evenly and reveal a uniform interior with a firm outer skin on both faces and a looser inner layer. There is no central cord, no elastic white thread running down the middle, and no sudden snap of a resistant core. That single test excludes a whole genus, as described below.

The Spore-Bearing Structures

Lichenised fungi do not build gills, pores or teeth, so the search here is for apothecia — small open discs where the fungal partner produces spores.

Scan the net with a lens. Apothecia sit on the faces and along the margins of the straps, often clustered near branch tips or scattered around the edges of the perforations. Each is a shallow disc 1 to 5 mm across, at first concave and cup-like, later flattening. The disc face is pale — whitish, buff or pale greenish, often looking slightly dusty — and it is rimmed by a raised margin of thallus tissue that has the same colour and texture as the strap it grows from, which is what makes it a lecanorine apothecium.

Not every population fruits, and heavily netted thalli in dense colonies are often sterile, so absence of apothecia is not evidence against the identification. Look for them on well-lit outer branches and on older, thicker strands.

Taking A Print, And What To Do Instead

A spore print in the mushroom sense is not achievable here. The spores are produced inside asci in an apothecium, released a few at a time, and there is never a bulk deposit to catch on paper. Substitute a squash mount.

Cut one apothecium off with a razor blade, place it disc-up, slice a very thin vertical section, and mount it in water under a coverslip. Press gently with the blunt end of a pencil and look at medium power. You are searching for asci — narrow cylindrical sacs — each containing eight colourless spores. In this species the spores are ellipsoid to slightly curved, thin-walled, and divided by a single cross wall into two cells. Alongside the asci are slender sterile filaments packed between them.

If you section the strap itself rather than the apothecium, you will see the layered construction that defines lichens: a dense fungal skin on both faces, a bright green band of algal cells just beneath, and a looser fungal medulla in the middle. The presence of a cortex on both surfaces, with no distinct upper and lower side, is another point of separation from the leafy lichens.

Substrate And Season

There is no fruiting season to time. A lichen is perennial and present all year, growing whenever it is wet and dormant when dry, so the practical question is when it is easiest to read rather than when it appears. Foggy mornings and the days after winter rain are best, because the thallus is pliable, greener and easier to handle without shattering.

Substrate is bark, and the species is not parasitic: it takes nothing from the tree and simply uses the branch as a perch. It draws its water and minerals directly from fog and rain, which is why its distribution maps so tightly onto the fog belt. Storm-fallen strands accumulate under heavily colonised oaks and provide the easiest study material.

Separating It From Look-Alikes On Structure Alone

Usnea species, the beard lichens, hang in the same places and can be a similar colour. The test is mechanical and takes two seconds: gently pull an Usnea branch apart and a tough, elastic, white central cord stretches between the two halves before snapping. Usnea branches are also round in cross-section rather than flattened, are often covered in tiny perpendicular side branches, and are never perforated into a net.

Other Ramalina species are the nearest relatives and share the flattened straps, the pale green-grey colour and the pattern of lecanorine apothecia. None of the common ones build a true net. Species like the farinose forms carry powdery soralia along their margins and branch tips instead, and their straps stay solid; if you find powdery patches shedding granular material and no perforations, you are in a different species.

Evernia prunastri is soft, strap-like and pendulous but distinctly two-sided: greenish grey above and conspicuously white or pale below, with a channelled underside, and it never perforates.

Bryoria and Alectoria hang in similar situations but their branches are round, thread-like and either dark brown to blackish or yellowish, with no flattening and no mesh.

Niebla species occupy the fog zone of southern coastal California and Baja and can be pale and strap-shaped, but they grow on rocks and low shrubs rather than hanging from tree branches, they are stiffer and more erect, and they lack the net.

Finally, do not mistake wind damage for structure. Any hanging lichen can be shredded into tatters by weather, but shredded straps have ragged, irregular, torn edges, while true perforations are smooth-margined, regularly spaced and repeated in a pattern across the whole thallus.