OLD MAN’S BEARD

Several years ago I saw a pictorial essay in the Sunday paper.
The article described a drive down beautiful Highway #1 from San
Francisco to Monterey. The first photo showed numerous
wildflowers and was captioned “Queen Anne’s Lace Graces the
Highway.” The flowers in question were actually Cow Parsnips. The
second photo said “Sea Lions Rest Peacefully on the Rocks.” They
were Harbor Seals. The final photo was entitled “Spanish Moss
Hangs from Windswept Pines.” The trees were really Monterey
cypresses. And draping from the trees were lichens called Old
Man’s Beard not Spanish Moss. They were batting 0 for 3 in the
photo department. I didn’t read the article.

Real Spanish Moss is found only in the southern United States–
along the Gulf Coast, in Georgia and in Florida. It isn’t moss
and it sure isn’t Spanish. It is a bromeliad, a member of the
pineapple family. Evolutionarily-speaking it is a highly evolved
plant with true roots, stems and flowers. Spanish Moss is an
epiphyte (on plant) not a parasite; it receives all of its
nutrients from rain water.

Old Man’s Beard on the other hand is a lichen, a primitive plant
found all over the world. They can tolerate extremely harsh
conditions. Some have been even found in Antarctica living inside
rocks! Considered pioneer plants, lichens are often the first
living things to colonize new surfaces. By secreting acids
lichens break down rocks and help convert them to soil. And like
Spanish Moss they receive all of their nutrients from rain water
or fog.

A lichen is not actually a plant. It actually consists of two
primitive plants — a fungus and an algae. The mnemonic device is
“Alice Algae took a Lichen to Freddie Fungus and now they live
together in a natural relationship.” Cute.

In cross-section a lichen consists of an outer protective layer,
a photosynthetic layer (individual cells of algae surrounded by
fungus), a storage area (for minerals and water) and a lower
cortex (that provides attachment).

Botanists used to believe that the relationship was a mutual one-
both partners benefited equally. The algae contributed sugars,
nitrogen and other nutrients to the fungus. The fungus in return
provided the algae a swell place to live with abundant water,
minerals and protection.

Now many scientists believe that Freddie is taking advantage of
Alice. The fungus is parasitizing the algae. The algae can live
just fine without the fungus but the fungus needs the algae in
order to survive. Not quite the idyllic relationship once
postulated.

Most lichens reproduce by soredia, microscopic bodies consisting
of tiny algae cells surrounded by fungus. These are formed in
special fruiting bodies and then released. Wind, water or even
animals transport these miniature lichens to new locations.

Scraping lichens off the walls is one job the maintenance workers
at the Transamerica Building do not have. In urban areas lichens
usually do not grow because of their sensitivity to air
pollution. They are especially susceptible to sulfur dioxide and
nitric oxide, two common by-products of internal combustion
engines. If you have lichens growing near your house in
Sonoma consider yourself fortunate, you breathe clean air.

After the Chernobyl nuclear accident large areas of northern
Europe were exposed to radioactive material. Reindeer moss, which
is actually lichen not moss, incorporated this fallout into its
tissues. The reindeer feed almost exclusively on these lichens.
Their flesh has become contaminated; it can not be eaten or sold.
The Laplanders who had depended upon the reindeer for centuries
suddenly found themselves out of a lifestyle. Because lichens are
so slow growing, it may be another 50 years before the reindeer
meat can be eaten again. Let’s not have any more nuclear
accidents.

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Skills

Posted on

August 23, 2009