Methuselah's Beard Lichen Identification Guide

First Impression and the Forest You Are In

This is a lichen rather than a fungus with a cap and gills, and the field approach is correspondingly different: everything happens above head height. You are standing in an old, humid, oceanic or boreal conifer forest, usually with spruce, true firs or hemlock, in a valley bottom, a riparian strip or a fog-fed slope where the canopy stays damp for much of the year. Looking up, long pale greenish-grey skeins hang from the branches like curtains, moving in the slightest air current.

The length is the immediate signal. Most hair lichens hang a few centimetres to perhaps twenty; this species routinely reaches half a metre to two metres, and exceptional strands have been recorded far longer. When you see draperies that long, uniformly pale yellowish green, festooning a single old branch, you are almost certainly in front of it. Because it is bound to old-growth structure and clean air, it is rare and declining over much of its former range, so most identifications are made on fallen fragments found on the forest floor after wind.

Overall Architecture

Pick up a fallen strand and lay it out on a flat surface. The structure is highly ordered and quite unlike a tangled beard.

There is a single long, dominant main axis, essentially unbranched along most of its length, running from the point of attachment to the tip. Off this axis, short side branches emerge at fairly regular intervals and at wide, near-perpendicular angles, giving a distinct fishbone or bottle-brush appearance. Those side branches are short relative to the main axis and may themselves divide once or twice, but they never take over as competing main stems.

That contrast between one very long primary strand and many short regularly spaced laterals is the architectural fingerprint. Most other pendulous lichens branch repeatedly and more or less equally, producing a tangled or dichotomously divided mass with no single dominant axis.

The Surface of the Main Axis

Examine the main axis with a hand lens. In most Usnea species the outer cortex is continuous and smooth. Here it is characteristically eroded: the cortex breaks up into transverse rings, annular cracks and irregular patches, exposing the paler medulla beneath. The effect has been compared to a stocking that has slipped, or to a series of loose sleeves along the strand. Toward the older, basal parts the cortex may be almost entirely lost, leaving long stretches of naked white medullary tissue.

That decorticate, ring-cracked main axis is one of the strongest single characters, and unlike the cord test it can be assessed without damaging the specimen.

Colour, Texture and Reproductive Structures

The thallus is pale yellowish green to greyish green, often bleaching to a straw or dull cream tone in exposed or long-dead material. The surface is dull rather than shining, and the texture is soft and pliable when damp, becoming brittle when thoroughly dry, which is why fallen strands fragment so readily underfoot.

The short side branches carry the reproductive structures. Look for soralia, small pale patches where the cortex has ruptured to release powdery granules of soredia, and in some material for small wart-like isidia. These vegetative propagules do the work of dispersal, and fragmentation of whole strands by wind does the rest.

Apothecia, the disc-shaped fruiting bodies that many lichens produce, are rare to effectively absent in this species. That is worth knowing before you spend time hunting for them: the absence of apothecia on an otherwise well-developed pendulous thallus is normal here.

The Spore Print Question and What to Do Instead

A spore print is not applicable. There is no cap and no exposed hymenium to invert onto card, and because apothecia are so rarely produced, sexual spores are seldom available at all. Reproduction is overwhelmingly vegetative, by soredia and by wind-broken fragments that re-establish on new branches.

The equivalent confirmatory procedure in the field is the cord test, and it is the one manipulation worth performing on every candidate strand.

Take a short length of the main axis between the fingernails of both hands and pull gently but steadily until it parts. Usnea species contain a tough, elastic, white central cord running down the middle of the strand, surrounded by a looser medulla and an outer cortex. When you pull, the outer layers break first and the white cord stretches visibly before snapping, exactly like the elastic core of a bungee. Alternatively, roll a piece between finger and thumb until the outer tissue crumbles away and the white thread is left.

A visible elastic central cord confirms Usnea in the broad sense. Its absence rules out the two most important look-alike genera outright, so make this the first test and the structural characters the second.

Substrate, Ecology and Season

The substrate is bark and, more often, the wood of branches: it drapes from the limbs of mature conifers, particularly in the mid to upper canopy of open-grown or edge trees where light and air movement are good but humidity remains high. It also occurs on hardwoods in some regions. It never grows on soil or rock.

Lichens do not have a fruiting season in the way mushrooms do; the thallus is perennial and visible year round. What changes is condition: strands are supple and vividly coloured in wet weather and brittle and pale in drought. Growth is slow and cumulative, so a long strand represents many years of undisturbed occupation of the same branch.

Ecologically this species is a well-known indicator of forest continuity and of clean air. It is highly sensitive to sulphur dioxide and other airborne pollutants and depends on stable humidity and old, structurally complex stands. Populations have contracted sharply in many regions following logging of old growth and historical air pollution. In the forest it contributes to the canopy epiphyte layer that intercepts moisture and nutrients, and it is used as nesting material by birds and as cover by canopy invertebrates.

Separating the Closest Look-alikes

Alectoria sarmentosa. The most frequent confusion, since it is also pale yellowish green, pendulous and abundant in the same forests. It has no central cord: pull a strand and it snaps cleanly with no elastic white thread, which settles the matter immediately. Structurally it branches more evenly and repeatedly, with no single dominant axis and no fishbone pattern, and its surface stays smooth and continuous rather than cracking into rings.

Bryoria species. Also pendulous and often abundant on conifer branches, but the colour is brown to dark chestnut or nearly black rather than pale green, the strands are much finer and more hair-like, and there is no central cord.

Ramalina thrausta. Pale green, pendulous and superficially very similar, with fine strands often ending in distinctive hooked tips. It lacks a central cord, and its branches are flattened or angular in section rather than round.

Other Usnea species such as Usnea filipendula, Usnea barbata and Usnea dasopoga. All possess the central cord, so the cord test does not separate them. Use architecture instead. They branch repeatedly and often dichotomously from a distinct thickened basal holdfast, tapering gradually toward the tips, and they seldom exceed a few tens of centimetres. Their main axes have an intact, continuous cortex without the transverse ring cracks. Crucially, the fishbone pattern of one very long axis carrying short regular perpendicular laterals is absent.

Usnea trichodea and related long species. Some southern and eastern species also grow long and pendulous. Look again at the main axis: continuous cortex and a more gradually tapering, more branched structure indicate a different species.

Field Checklist

• Old humid conifer forest with high canopy continuity and clean air
• Strands pendulous and very long, commonly 0.5 to 2 m
• One dominant main axis with short, regular, near-perpendicular side branches: fishbone habit
• Main axis cortex cracking into transverse rings, exposing pale medulla
• Pale yellowish to greyish green, dull, soft when damp and brittle when dry
• Soralia and isidia on side branches; apothecia rare or absent
• Gentle pull reveals an elastic white central cord