California Lichen Society

A delightful group for lichenophiles across California, from newbie to expert, from weekend dabbler to professional lichenologist. CALS has events (including a terrific annual meeting in January), a bulletin, student scholarships, lichen merch, and more.

Visit the CALS Website →

Lichen ID and General Education Web Resources

The Australian National Botanic Gardens has a great (if dated-looking) lichen website–especially good for lichen reproduction: https://www.anbg.gov.au/lichen/

Virtual Macrolichens of the Pacific Northwest key by McCune–(author of the print book of the same name)–it’s a little different than a typical dichotomous key but it’s very neat and a great tool: https://lichens.twinferntech.net/pnw/select.shtml. 

Lichens sorted by morphogroup (Trevor Goward’s webpage)

Tom Carlberg’s Key to the Macrolichens of the Central California Coast

iNaturalist (website & app)
Many lichenologists and lichen enthusiasts are active on iNat. It’s great to post lichen observations and explore those of others. Try it out and see what lichens have been reported around places you live or travel (search “Fungi including lichens” or “Lecanoromycetes”). Be aware that lichens are often identified by amateurs, and identifications on iNaturalist are often unreliable (Seek, the auto-identification tool, is very cool but not likely to work as well for lichens, since it is based on what’s in the database and there are only so many lichen observations, but it has improved over time, I think). Nonetheless, it is a cool community science tool, a great way to find good lichen viewing spots, a great way to peruse a lot of lichen pictures, and a good way to connect with other people who are looking at lichens.

Recommended Online Readings (news articles, scientific papers, and other readings by topic)

My favorite starter read that I return to again and again:

“Face in the Mirror” by Trevor Goward — a fun, sort of conceptual/philosophical take on lichens (there are 11 more essays where this one came from if you like it). I have all of my students read this the first week.

Lichen ID and Biodiversity:

• A scientific paper from 2017 with recent statistics on lichen biodiversity statistics and nice discussion of what constitutes a lichen, how we classify it, evolution, etc. (Long and detailed but worth a skim, especially the beginning.)

Lichen Evolution and Fossils:

• A New York Times article from 2019 on the origins of modern lichens
• Cool 2017 Scientific American article on new fossils found in amber
• News article on Science Daily about lichen diversification after the end Cretaceous extinction event

Lichen Ecology (Abiotic Relationships) and Air Quality:

• This paper summarizes lichen adaptations to extreme environments–relatively readable
• This paper summarizes lichen research about climate change effects
• News article on lichen testing under Martian conditions
• NYTimes article with fascinating tale of how mosses were used to study pollution in Portland (mosses, not lichens, but very similar to how lichens can be used)
• Our paper about lichen recovery after fire in chaparral (published in 2021)
• A really fun article about Southern CA lichen expert Kerry Knudsen
• User guide for the Forest Inventory Analysis Lichen Community Indicator–long but worth a skim or reading sections if this is a topic that interests you
• A nice paper that summarizes how lichens influence the environment--I especially like the figure on page 3. It also addresses influences of animals/food webs.

Lichen Relationships with Animals, Plants, and other Lichens:

• This news article discusses a variety of lichen topics, including competition between lichens, but will also introduce you to some of the ways people use lichens
• Smithsonian story of how mercury has traveled from fog to lichens to deer to mountain lions in California
• A scientific paper about radioactive isotopes (radionuclides) in the lichen-reindeer-human foodchain–a bit dense, but check out the introduction and maybe the discussion/conclusion for a general idea
• Here’s an article on reindeer seeing in UV
• A scientific paper summarizing lichen-plant interactions–a fair bit of jargon but worth a skim if this topic interests you
• A scientific paper on lichenicolous fungi–the intro and first section on interactions with lichens are quite interesting.
• A scientific paper that reviews competition in lichens-worth a skim if this interests you

Humans and Lichens:

• A database of records on human uses of lichens
• A review of the biopharmaceutical uses of lichens (a little old considering the topic, but one of the more comprehensive and readable ones I’ve found)
• A neat little article in Wired about oakmoss and changes in the perfume industry
• A guide to getting started with lichen dyes

Lichenologists and their lives:

• The Unsung Heroine of Lichenology
• The Ex-Anarchist Construction Worker Who Became a World-Renowned Scientist

Lichens and Basidiomycete Yeasts and Other Mysteries of Modern Lichenology:

• Toby Spribile’s 2016 paper that changed it all 
• A story in The Atlantic about the discovery (also listed above)
• Another great article in the Atlantic about Tremella, other possible partners, and microbiomes
• A paper that nicely summarizes the concept of many fungi in lichens, using the metaphor of a “choir of fungi”
• The lichens as 3D biofilms paper –gets pretty hairy for casual reading on the details of the biochemistry, but at least worth checking out the introduction and skimming the section on organismal uptake and inputs to get the gist of the argument

Books and Book Chapters

Macrolichens of the Pacific Northwest (McCune and Geiser) — Best ID book with keys for northern CA and the PNW, does not include crustose lichens. Includes good intro information on lichens and air quality analyses and an excellent illustrated glossary. For crusts see Microlichens of the Pacific Northwest Volumes 1 & 2 (McCune).

A Field Guide to California Lichens (Sharnoff) — Best overall coverage of California lichens, including both macrolichens (foliose and fruticose) and microlichens (crusts). No keys, but decent photos and descriptions and an excellent introduction to lichens at the beginning.

Urban Lichens (Allen & Lendemer) — This is for the Northeast but I love this book’s emphasis on urban lichens. I hope there will be a Western version in the future!

Lichens (Purvis) — A very short book that nonetheless provides a great overview of lichen biology. It’s a bit old, but most of the basics hold up. I especially like its photos of lichen cross-sections under the scope, one of the only resources I know that shows photos of the internal structure of different lichen growth forms, including fruticose lichens and stratified vs. non-stratified lichens.

Lichen Dyes: The New Source Book (Diadick Casselman) — Essential little guide if you want to get into dyeing, with information of colors and approaches for many different species.

The Lichen Museum (Palmer) — A contemplation and examination of how humans have understood lichens over the centuries. It definitely reads like it was written by a professor from UCSC (can get a bit overly academic, progressive values shine through), because it was. But it’s short enough that wading through academese isn’t too much of a chore and it’s terrific food for thought for anyone. It has a lot of fascinating lichenological history that I haven’t encountered elsewhere.

Lichens of North America (Brody, Sharnoff, and Sharnoff) — A big fat expensive book that I only have because a friend happened to have a copy she wasn’t using and asked if I wanted it. But it is beautiful and comprehensive. And very heavy.

“Umbilicaria: The belly Button of the World” in Braiding Sweetgrass (Kimmerer) — The whole book, which is primarily about plants, is worth reading but it has a wonderful chapter about lichens and in particular, Umbilicaria. It’s about indigenous use of this lichen but also more generally about human relationships with lichens, from practical use as food to how we relate to and understand the world. I always have my students read this chapter, towards the end of the course, and then write their own contemplation about their relationship with lichens so far, and reading those is always a delight.

“The Intimacy of Strangers” in Entangled Life (Sheldrake) — This book is all about how cool fungi are, and it has a very good lichen chapter. The book tells its stories by focusing on specific experiments or researchers, weaving the more general fungal and lichen biology in around those stories, and in the lichen chapter the focus is on a project that sent lichens to space, but there’s a lot of writing about the nature of lichens in there, too.

Social Media Groups and Pages

Facebook Groups
These groups are a great way to see a lot of great lichen photos from around the world, often with IDs. Take the IDs with a grain of salt, though—it’s hard to get definitive IDs from photos, and experience levels of those who comment can vary widely.
o Lichen Identification
o Lichens Connecting People!
o Ferns, Lichens, and Mosses
o Mushroom and Lichen Dyers United (if you are curious about dyeing)

Instagram
There’s not as much of a lichen community here as on Facebook, but there are definitely some good accounts to follow for even more lichens in your life!
Here are a few that I like:
o calichens (the CALS page)
o nwlichens (NW Lichenological Society page)
o liquenspain
o lichensornot