Lichens: Mystery in Plain Sight

February 20, 2023

Lichens are like the teenage boys of the plant world — they can live pretty much anywhere under any conditions. They make their home on rocks, trees, soil, houses, concrete, even old cars or equipment. If water is scarce, lichens survive by becoming brittle and dormant. Then when water is available, they come alive again and continue to photosynthesize. Though adaptable and low-maintenance, they have been a source of mystery and wild discovery for botanists during the last two centuries. One such discovery occurred in 2016, when Toby Spribille, a young scientist fascinated with lichens, upended 150 years of thought. And curiously, his path to discovery resembled his predecessor’s a century and a half earlier.

Lichens have a long history of vital uses, providing food, shelter and nesting material for birds, insects, deer, rodents and other animals. Humans have also used lichens for food and to make clothing, medicine, dyes and perfumes. Lichens provide data used to determine trends in temperature and precipitation changes. They also absorb pollutants, and scientists use them to determine levels of heavy metals, carbon, sulfur and other harmful elements in the environment.

Often confused with mosses, lichens are not plants and have no roots, stems or leaves. There are three types of lichens: foliose (leafy); fruticose (hairlike, cuplike or shrubby); and crustose (like crust). Species we often see in SHR’s garden include: Usnea strigosa or the bushy beard; Cladonia species such as British soldiers and reindeer lichens; Physcia species or foliose lichens; and Lobaria pulmonaria or lungwort lichen.

Before Toby Spribille burst onto the scene, scientists long believed lichens were made of a partnership between fungi and algae, thanks to groundbreaking work by Simon Schwendener in the 19th century. Born in 1829 in a small northern Switzerland village, Schwendener, as the only son, was expected to take over his family’s farm but was drawn to science instead. He supported himself as a grade schoolteacher for many years while attending science classes at the University of Geneva. Eventually he made his way to university studies and began microscopic research on lichen at the University of Munich in 1857. Ten years later, he presented his hypothesis that a lichen is not a single organism but in fact a fungus and an alga in relationship.

For several years, lichenologists rejected and even attacked Schwendener’s hypothesis, but it burst wide the imagination of biologists and botanists, who began thinking in dualities. German botanist A.B Frank coined the term “symbiosis” — popularized later by German microbiologist Anton de Bary — to describe the relationship between mycorrhizal fungi and tree roots. The concept of symbiosis was the key to understanding the function of many species of plants and animals.

Much like Schwendener, Toby Spribille felt the lure of science early on but had no straight path available to pursue studies. Raised and homeschooled in a Montana trailer park, Spribille was fascinated by lichens and collected them like baseball cards. Like Schwendener, he found his way to Germany and the University of Gottingen, which occasionally under special circumstances would enroll students with no transcripts. After earning a doctorate, he returned to Montana and began studying two types of “horsehair” or “treehair” lichens, Bryoria tortuosa and Bryoria fremontii. The two have identical gene structure but one is brown and benign and the other is yellowish green and poisonous. Scientists had long tried to recreate lichens in laboratories by combining an ascomycetous fungus and a photosynthetic alga — but it never worked. When Spribille looked more closely at the two horsehair lichens, he discovered a third component: a basidiomycetous yeast.

The surprises do not end there. A few years later, scientists discovered another fungus known as Tremella as a partner in wolf lichens, completely missed in one of the most extensively studied lichens. These continued discoveries lead experts to call lichens “ecosystems as well as organisms,” as described by Anne Pringle, a botanist at the University of Wisconsin at Madison.

Schwendener retired in 1910 at the age of 81 from the University of Berlin and lived nearly a decade more. He served as benefactor for many younger scientists and supported the work of female graduate students at a time when they were often escorted out of lecture halls simply for being female.

Spribille continues his research as assistant professor of biological sciences at the University of Alberta in Edmonton. Both dedicated scientists remind us that discovery and surprise can occur if we expect the unexpected, look closely and keep open our eyes and minds. Partnerships and interconnectedness are always present in nature.