Witch's Hair Lichen Identification Guide

First Impression and Setting

You usually meet Alectoria sarmentosa before you meet the tree it fell from. In a wet, mossy conifer forest — coastal hemlock and spruce, interior fir and larch, or northern boreal spruce — the ground after a windy night is scattered with pale, straw-green tangles that look like combed hair. Look up, and the same material hangs in long skeins from the lower limbs and dead branch stubs, thickest on the shaded, humid side of the crown. The overall impression is of a pendent shrubby lichen, soft and lax rather than stiff, coloured somewhere between pale yellow-green, straw and greenish-white. Nothing else in a damp conifer forest hangs quite so long, quite so pale, and quite so evenly.

Reading the Branching Pattern

Spread a single tuft on a dark sleeve and follow one strand from base to tip. The branches are terete — round in cross section — along most of their length, flattening and becoming slightly angular only at the forks. Branching is repeatedly dichotomous: each branch divides into two roughly equal arms, and those divide again, so a mature tuft resembles a many-times-forked stream rather than a plume with a dominant central axis. Strands taper steadily into long, fine, tangled tips. Individual branches usually measure 0.3 to 1 mm thick near the base, and a whole tuft is commonly 10 to 30 cm long, occasionally reaching half a metre in old, sheltered stands.

The Pull Test

The single most useful manipulation in the field costs you one branch. Hold a strand between two thumbnails set about a centimetre apart and pull slowly. Alectoria is hollow to loosely packed inside and has no elastic core: the strand parts cleanly, leaving two dry, even ends. Usnea, the other pale pendent hair lichen of the same forests, contains a tough white central cord that stretches like a rubber band before it snaps, peeling the outer tissue back on both sides. Perform this test once on any pale hanging lichen and you have settled half the identification before you have looked at anything else.

Surface Detail: Pseudocyphellae and Soralia

Now bring a hand lens to the strand. The surface is smooth and faintly glossy, marked with pseudocyphellae — small, raised, chalk-white pores that appear as short lines, spindles or low ridges scattered irregularly along the branches. These are gas-exchange breaks in the outer skin and they are a genus-level signature. Mature material also carries soralia: rounded to slightly elongate warts that rupture and release a granular whitish powder of soredia, the vegetative propagules. In this species the soralia are tubercular and scattered along the branches rather than crowded at the tips. Wet the lichen and the whole thallus softens, turns a clearer green and goes limp; let it dry and it stiffens and pales. Judge colour on damp material so your comparisons stay consistent.

Apothecia, and Why There Is No Spore Print

The routine built around gills and spore prints does not transfer to lichens, and it is worth understanding why. Alectoria sarmentosa reproduces overwhelmingly by fragmentation and by soredia; sexual fruiting bodies are genuinely uncommon. When they do appear, they are apothecia — flat to shallowly saucer-shaped discs 2 to 8 mm across, seated laterally on a branch, with a pale yellowish to light brown face ringed by a rim of thallus tissue that often bears a fringe of tiny branchlets. There is no practical way to make a print from them, and no need. Record their presence, their lateral position and their pale disc as bonus characters. The lichenological equivalent of the print is the chemical spot test: dabs of potassium hydroxide, bleach and para-phenylenediamine on the outer and inner tissue produce colour reactions that separate the fussier segregates in this group.

Substrate, Habitat and Season

This is a canopy epiphyte of cool, humid, clean-aired conifer forest. It grows on bark and on dead branch wood of spruce, fir, hemlock, Douglas fir and pine, favouring the lower and middle canopy of mature stands where fog and rain hold moisture for long stretches. It is strongly associated with structurally complex old forest and thins out quickly in young plantations, on dry ridgelines, and anywhere the air carries industrial pollution. Lichens have no fruiting season in the mushroom sense: the same tufts persist and enlarge slowly over many years, so the species can be found in any month. What changes seasonally is your access to it — the best material arrives on the ground after storms, windthrow and limb fall.

Separating the Look-alikes on Structure Alone

Usnea species share the pale yellow-green colour and round branches but always contain the elastic central cord. Many also grow with a distinct main stem bearing short side branches, giving a bottle-brush look, and their soralia are often flush, disc-like patches rather than raised warts.

Bryoria species are identical in habit but coloured chestnut, olive-brown or nearly black, with much finer, wirier branches and inconspicuous pseudocyphellae. Colour alone separates them at arm's length.

Alectoria vancouverensis is the closest relative in coastal forests. Its branches are conspicuously flattened and angular along much of their length rather than only at the forks, and its pseudocyphellae are longer, more prominent, and mostly restricted to the flattened faces.

Ramalina thrausta is pale yellow-green and pendent, but far finer and more sinuous, with distinctive hooked, curled branch tips ending in small globose heads of soredia. It lacks the linear white pseudocyphellae entirely.

Evernia prunastri is pale green above but strap-shaped, flattened, and clearly paler and channelled beneath. It is a two-sided lichen, whereas Alectoria looks the same all the way around a branch.

A Working Checklist

Pendent tufts hanging from conifer branches; pale straw to yellow-green throughout; branches round, dichotomously forked, tapering to fine tips; no elastic central cord on the pull test; raised white linear pseudocyphellae under a lens; scattered wart-like soralia; apothecia rare, lateral and pale-faced; humid mature conifer forest. Score all eight and you can leave the tuft where it hangs with confidence.