Devil's Matchstick Lichen Identification Guide

The setting you will be standing in

This is a lichen of wet, shaded, rocky places in cool coastal forest. Picture a mossy roadcut through conifer woodland in the Pacific Northwest, a boulder field beside a creek, a shaded cliff base, or a scatter of stable rocks under hemlock and Douglas fir where the air stays humid for most of the year. The rock matters: it is a hard, acidic, non-calcareous stone — basalt, granite, andesite, quartzite, sandstone — never limestone.

What draws your eye is texture rather than colour. Across the rock face there is a greyish-green crust, and standing out from it, catching the light, are dozens of tiny pale stalks each tipped with a hard black bead. From a metre away it looks like a scatter of spent matches stuck upright in lichen. Get your knees wet and your hand lens out, because everything useful is at the two to twenty millimetre scale.

Step one: the crust at the base

Start at the bottom, not the top. The primary thallus is a crust that sits directly on the rock: granular, warty or minutely lumpy, and pale grey-green to olive-grey, sometimes almost whitish when dry and noticeably greener when wet. It has no leafy scales, no lobes and no free edges lifting away from the stone. This is important, because the presence or absence of scales is the fastest way to split it from the biggest look-alike group.

With a lens, hunt across the crust for small, dark, bluish-grey to blackish nodules sitting on or in it. These are cephalodia, discrete pockets holding a second, cyanobacterial partner alongside the green algal partner that occupies the main thallus. They are not always easy to see, but finding them is strong confirmation and it also explains one of the species' ecological roles.

Step two: the stalks

The upright structures are pseudopodetia — stalks built of fungal tissue that rise from the crust. Assess them methodically.

Height: typically 5 to 20 mm, occasionally to 30 mm in sheltered, humid sites.

Form: slender, cylindrical, usually simple and unbranched, straight or slightly curving, tapering only a little toward the top. Some populations show occasional forking, but a stand dominated by heavily branched stalks should make you consider other species.

Surface: pale grey-green to grey, finely granular to slightly roughened, matt rather than shiny, and solid rather than hollow. Snap one between thumbnails: it should be firm and pithy through the middle, without the open tube you find in some superficially similar groups.

Step three: the black head

This is the character that names the species. Each mature stalk ends in a single, hard, jet-black, more or less spherical to slightly flattened apothecium — the fruiting body — one to two millimetres across, usually a little wider than the stalk beneath it.

Look at it wet and dry. It stays black in both states, and it is smooth and often shiny, giving the exact impression of a burnt match head. It is carbonaceous and brittle rather than fleshy; press a needle against it and it resists, then cracks.

Check how the head sits. It should be terminal — perched on the very tip — not scattered along the sides of the stalk and not clustered in a group of several small discs. A stalk carrying several brown discs in a cluster at the top is a different genus.

Step four: what to do instead of a spore print

A lichen will not give you a spore print in the usual sense, and there is nothing to lay face down on paper. The equivalent step is a squash mount.

Remove one black head with fine forceps, put it on a slide in a drop of water, place a coverslip over it and press firmly with the blunt end of a pencil until the head flattens and spreads. Under the microscope you are looking for a hymenium with a very dark upper layer and, within it, asci containing eight colourless, simple, smooth, elliptical to spindle-shaped ascospores. The blackness of the head comes from heavy pigmentation in the tissue, and seeing that dark layer over a paler layer beneath is itself confirmatory.

Standard chemical spot tests contribute little here; morphology does the work, and you should not need reagents to place a well developed specimen.

Step five: substrate, moisture and season

Record the rock type, the aspect and the moisture regime, because habitat is part of the identification. Expect hard siliceous rock, often shaded, often within reach of spray from a creek or of persistent fog, frequently on north-facing or otherwise sheltered surfaces, and usually in the company of mosses, other crustose lichens and liverworts.

Unlike mushrooms, lichens are perennial and there is no fruiting season to wait for; the same colony can be examined in any month. The practical constraint is moisture. Dry material is pale, brittle and hard to read, so carry a small water bottle and wet a patch, then wait a minute for the crust to swell and green up before you judge colour and texture.

Separating it from look-alikes on morphology alone

Cladonia species. The largest source of confusion, since many produce upright stalks from a basal thallus. Two differences do the work. First, the base: Cladonia species almost always have a primary thallus of distinct leafy scales, or squamules, with free edges lifting from the substrate, whereas ours is a granular crust with no scales. Second, the stalk: Cladonia podetia are hollow tubes, frequently expanded into cups or branched into candelabra shapes, and their apothecia are usually brown or bright red and often several to a tip. Ours is a solid, simple stalk with one hard black head.

Stereocaulon species. Also produce upright pseudopodetia from a base, but theirs are usually branched and clothed in phyllocladia — small granular or scaly outgrowths — often with a felty or woolly covering, and their apothecia are typically dark brown, irregular, and produced in clusters rather than as a single polished black bead on an unbranched stalk. Stereocaulon also frequently grows on soil and gravel as well as rock, in more open situations.

Other members of its own genus. These are the genuine challenges. Relatives may have stouter, sometimes branched or club-shaped stalks, coarser and more granular basal crusts, apothecia that are broader and more irregular than a neat sphere, or, in some, a basal thallus that tends toward small scales. Judge slenderness, simplicity of the stalk, and the neat rounded black head at the tip, and note the stalk-to-head diameter ratio.

Pink-headed stalked crusts. Several unrelated lichens form a granular crust on soil or rock with short stalks bearing apothecia, but their heads are pale pink, flesh-coloured or pinkish-brown rather than black, and the stalks are usually shorter and paler.

Club-shaped basidiolichens. Small clubs rising from a green film on soil or rotten wood look similar at a glance, but they are pinkish, orange or yellowish, smooth and waxy in texture, taper to a point rather than to a bead, and lack a black tip entirely.

Worm lichens and coral lichens. Whitish or grey upright forms on soil that lack any fruiting head at all, or that branch repeatedly; a single black terminal bead is not present.

Field summary

Granular grey-green crust on hard shaded siliceous rock; dark bluish nodules on the crust; slender, simple, solid grey-green stalks 5 to 20 mm tall; one hard, shiny, jet-black spherical head at each tip; cool humid coastal forest; no leafy scales at the base; no cups; no branched candelabra. Run those in order and the identification is comfortable in the field.