7 Jan 2022

The Lichening Rod

Ardd Fotaneg · Botanic Garden

Long assumed to belong in the plant kingdom, in 1868 Swiss botanist Simon Schwender discovered that lichens are actually composite organisms: a symbiotic relationship between a fungus and an alga.

This “dual hypothesis” began to chip away at the widely accepted boundaries of what we think a species really is. Even to this day, lichens continue to poke holes in the dogmas of modern science and reveal profound gaps in our perspective of what constitutes an individual organism.

In foliose lichens (more on that later) those single-celled algae have been found to live within a distinct layer within the lichen body. This can be seen in the cross section pictured above, prepared in the labs at the Science Centre.

“Lichens are places where an organism unravels into an ecosystem and where an ecosystem congeals into an organism.”

– Merlin Sheldrake

The more lichens are studied, the more complex they seem to become, and the more light they shine on the shortcomings of a strictly biological perspective. The lichening rod effect is a term coined by the curator of the University of British Columbia’s lichen collection, Trevor Goward. It describes the “supercharged understanding” that follows in the wake of when lichens “strike familiar concepts, splintering them into new forms”.

As recently as 2016, the baseline biological understanding of lichens was broken yet again; this time by American lichenologist, Toby Spribille. He discovered a third player in the lichen game: a basidiomycete fungal yeast. Previously, only one type of fungus (an ascomycete) was thought to exist in each lichen. Spribille has beautifully proven that there is almost always another fungus hiding in single-celled form within the body of the lichen. Furthermore, he suspects that more species will be discovered in the future. His discovery extends far beyond just the complex biology of the lichen. In the words of Merlin Sheldrake:

“To talk about individuals made no sense anymore. Biology— the study of living organisms—had transformed into ecology—the study of the relationships between living organisms.”

– excerpt from “Entangled Life”

That is to say, a lifeform once believed to be a single species has turned out to be a coalescence of distantly related organisms; who’s to say that this school of thought won’t splinter other commonly known individuals into multi-species organisms. What really constitutes the individual? Is the term “species” obsolete? Given that there are more bacterial cells in our body than human cells, are we really individuals or entire ecosystems? We could go on . . . the lichening rod strikes again, providing a powerful tool to rethink and redesign the pillars that support our current understanding of the natural world.

Once you truly open your eyes to lichens, you’ll soon find them everywhere you look: on wooden railings, concrete floors, rusting metal surfaces, and even glass windows, not to mention almost all niches of the natural world! Often overlooked as mere flecks of dirt, grime or dust, these peculiar organisms are pivotal in the upkeep of life as we know it. Through both mechanical processes and the production of potent acids, lichens break down any surface they inhabit, producing the first soils in a new ecosystem. This unique and valuable ability to pass inorganic matter into the metabolic world of the living make lichens a key cornerstone player in the earth’s dynamic processes through geologic time.

If you’ve made it this far then you might be interested in the different types of lichens that you can go out and find for yourself. There are three main lichen morphologies (all of which are pictured in the Garden at the top of the page!):

  • Foliose

Sitting atop their substrate, these lichens have a flat, leafy texture and are generally anchored down by rhizines all across their underside with outer lobes lifting away from the substrate. They often have two distinct colours on the upper and lower sides.

  • Fruticose

With a 3D structure and branching, tree-like forms, these lichens either stand up away from the substrate or hang down off of twigs in long, wispy filaments.

  • Crustose

Embedded within the surface layer of rocks, bark or wood, these lichen forms can often seem like they are part of the substrate itself. They’re completely flat and can be found in an amazing array of colours; from orange, to red to neon yellow! Often covered in small speckles or dots which are the fungal fruiting bodies.

With great air quality and array of plant and rock types, the Botanic Garden is a great place to come looking for lichens. While you are here, see if you can find the transplanted lungwort lichen (Lobaria pulmonaria), near Tarw the black bull sculpture close to the Great Glasshouse. Try and spot the array of crustose lichens embedded throughout the Rock of Ages display on the Broadwalk. Finally, be sure to visit the Oriel Yr Ardd Gallery in the Stable Block, currently displaying the “I Spy Lichen” exhibition. Created by the members of Stitching Botanical, this awe-inspiring display creatively blends art with science.

We look forward to seeing you soon!