Guest Post: Lichens at the Garden

Last week, I received the November Newsletter from the Friends of Regional Park Botanical Garden.  The garden, inside Tilden Regional Park in the east bay, has a truly astounding collection of plants from all-over California. Friends of Regional Park send out a newsletter several times a year and offer classes.

Because I was so impressed with the information, I asked to reprint the article on this blog, and John gave permission. You can go to the botanical garden and use the directions to find the different lichen, or just enjoy the photos that were included in the newsletter. The copyright to text and photos belongs to Friends of Regional Park Botanical Garden.


Ah, lichens! What are they? Fascinating, intriguing life forms with marvelous colors and different structures! Worldwide there are about 14,000 species found in all kinds of diverse physical environments. In California, there are about 1000 to 1500 species.

Lichens are symbiotic entities. Their outer structures are fungal, enclosing inner algae and with or without outer or inner cyanobacteria. Lichens are named after the fungal component. Fungi use absorption to obtain their nutrients while algae and cyanobacteria make their own food. In the lichenized form, the fungi obtain nutrients from the algae and nitrogen from the cyanobacteria. Current research also shows that lichens have relationships with non-photosynthetic soil bacteria that provide essential minerals for growth. Fungal reproductive structures, asexual and sexual, are on the surface and are used to identify lichens. The enclosed algae reproduce only asexually by cell division.

At the Garden, lichens are everywhere. Sensitive “creatures,” their presence indicates that the air quality in the Garden is very good. To explore, we need to walk slowly and search out bright or subdued colors on rocks, tree trunks, tree branches, fencing, and soil. Lichens adhere to all surfaces and some dangle from branches.

You can find most of the six groupings of lichens at the garden.  The group name describes a lichen's general shape and surface structures: foliose, fruticose, crustose, squamulose, leprose, and gelatinous.

Some of the lichens you will find on a walk through the Garden are shown below. (A hand lens is helpful.)

Foliose lichens

Xanthoparmelia cumberlandia, on rock wall behind Garden sign, “What Makes Your Garden Grow,” east of the deck facing the north side of the Visitor Center, that is, to the right of the dwarf Garry oak and before the California Copperleaf shrub.

Parmotrema arnoldii, bed 927, on vine maple

Parmelia sulcata, bed 927, on vine maple

Fruticose lichens

 Usnea arizonica, on black oak tree branch just above the Sierran Meadow sign, bed 616

Teloschistes chrysophthalmus, bed 927, on vine maple

Crustose lichens

Thelomma mammosum, bed 733, on rock wall in front of the nursery

Squamulose lichens

Cladonia chlorophaea, bed 925

Cladonia macilenta, bed 650 or 651, on ponderosa pine trunk just above the soil
Leprose lichens

Lepraria lobificans, on redwood tree trunk, bed 726

Chrysothrix candelaris, on oak tree in the Garden's parking lot

If you are curious to observe more lichens, you can join us at the Garden’s lichen workshops, the second Saturday of each month, from 1 to 4 pm.

Happy lichenizing -- or to use Trevor Goward’s expression, “try enlichenment.”

--Irene Winston


Unknown said…
We live in the midst of a forest, and the article was so interesting! I've often wondered exactly what lichen were growing...thanks for sharing this resource.
ryan said…
That's great. I always appreciate them, but I've never known any of the species.
Dear TM and CM, I am so glad you were able to share this article. It is so informative and the photos are stunning. Pam x