Get Growing with Mickey Rathbun: No sprouts yet, but there’s always lichen to count on

  • Scaly lichen growing on rocks in the Oak Hill Conservation Area in Littleton. Flickr/Paul Morris

  • Lichen growing on a rock wall on the Cape Cod community of Dennis. Flickr

  • British Soldiers lichen, Cladonia cristatella, at Meadowood Farm SRMA in Mason Neck, Virginia, in November 2017. Judy Gallagher/via Wikimedia

Monday, March 28, 2022

This time of year, my entire body yearns for spring. A few days of warmish weather tease me into thinking that we’re done with winter. But March is a fickle month in New England: in like a lion, out like a tiger.

I am desperate for the early skunk cabbages to send forth their purple and green speckled spathes (that’s the open pod that enfolds the flower like a cloak) in the wetlands that flank the rail trail where I walk my dog. No sign of them as of this writing.

In these dreary days when the landscape has for so long been leached of color, I have a renewed appreciation for lichen. In the local landscape it appears in several forms, from shaggy, irregular patches to smooth paint-like splatters, in various muted shades of green and gray. It doesn’t shout for your attention, but once you see it, lichen is endlessly entertaining to the eye. And it’s everywhere.

I have been aware of lichen since I was very young. I have a dim memory of my mother pointing it out to me. The name stuck in my mind like a burr; I felt very grown up when I said it. But I never bothered to learn much about it, beyond the facts that it is not technically a plant and can live for a very long time.

The other day, after noticing healthy coats of lichen on some stones in the garden, I decided it was time to educate myself about this ubiquitous organism.

The word lichen is derived from the Greek word “leikhen,” which means “what eats around itself.” Lichen is not a parasite. It’s a combination of algae and fungus that form a mutualistic relationship. The alga is the partner that performs photosynthesis, “the photobiont.” When lichen is wet, the surface becomes more transparent, letting the inner photobiont shine through. This brightens the lichen’s color, sometimes making it seem to glow. (I hope that lichenologists will forgive me for this oversimplification.)

Lichen are among the oldest living things on earth. There are at least 20,000 species, which all told cover 6-8% of the earth’s surface. The earliest known specimen, dating from the Early Devonian period (400 million years ago), was discovered in Scotland in the early 20th century in an unusually rich fossil bed called the “Rhynie Chert.” (I couldn’t resist that name.)

Lichen is also one of the hardiest living things on earth. It is found everywhere from sea level to the tallest mountain peaks. A few species even grow permanently submerged in water. It survives every environmental condition including Arctic tundra, rainforest, and dry desert. It even thrives in gritty urban areas.

And it isn’t at all choosy about the surface on which it grows (its “substrate”). Lichen will grow on virtually any undisturbed surface, whether manmade or natural. It likes plastic, metal, rubber, cloth and even glass. It also finds a home on moss, soil and decomposing leaves.

The lichen’s substrate needs to be undisturbed over a long period of time because lichen grows very, very slowly, increasing in size by around one millimeter a year. This is why we most often see it on rocks and trees. Next time you’re in a graveyard, notice how lichen takes up residence on headstones, adding a lovely, subtle patina to the steadfast markers.

Exposed rock faces make excellent substrates for lichen. In fact, Mount Rushmore is a hotbed for lichen and needs to be cleaned regularly by mountain-climbing conservators. (Personally, I think those huge carved granite faces could use a bit of color.)

Most of the lichens we see around here are grayish green in color. But other species have special pigments that give them colors in the yellow-orange-red-brown spectrum. And there are many different lichen formations. There are three-dimensional leafy varieties. Some lichens are crusty, like hardened thick paint. Others are powder-like in appearance. There are even gelatinous lichens and some that hang from tree branches in the fashion of Spanish moss.

But the most stunning lichen of all is called British Soldiers. It grows in clusters of hollow upright stems topped by bright red fruits. I’ve never seen the real thing, but I understand that it grows on dead wood and on the ground and its colors are most vibrant in early spring.

Patterns also vary. Some lichens radiate out from a central point, forming orderly round patches. But many grow in random spots and splotches, creating odd shapes that lend a decorative, improvisatory aspect to their substrates.

As I look at them, it’s hard to imagine that once, long ago, they were tiny specks that have grown steadily, indefatigably, and virtually imperceptibly from year to year. It’s good to remember the pace of lichen growth when lamenting the slow growth of a new tree.

Lichens have more to give than visual delight. In some parts of the world, they have been eaten in times of famine and even as a delicacy. Unfortunately, many are toxic. One species is used in some traditional Japanese and Korean foods. Reindeer subsist on a type known as reindeer lichen. Denizens of Siberia and northernmost North America have been known to eat partially digested reindeer lichen taken from the rumen (the first of four stomachs) of a freshly killed reindeer. Enough on that subject.

Dyes in various shades of purple are made from a type of white, moss-like lichen known as “orchella weed” that grows abundantly in the Canary and Cape Verde islands. According to a treatise on merchandise published in 1805, this dye property was discovered around 1300 by a Florentine merchant who was relieving himself on a patch of this lichen and noticed that it turned bright red.

The story goes that his family, the Rucellai of Florence, came up with a process for making purple dye. They kept the formula secret for many years, becoming very wealthy on the sales of purple fabric and wool.

I’m always amazed that such a simple-seeming thing as lichen can be so richly complex. Quiet and unassuming, it is one of the true wonders of nature.

Mickey Rathbun, an Amherst-based lawyer turned journalist, has written the “Get Growing” column since 2016.