Monday, August 24, 2009

Moss & lichen (mainly lichen)

These are definitely not today's photographs -- or yesterday's -- though I would normally expect such lush mosses in late August. However, we've not had our usual summer moisture this month; these photographs date from a happier time. The mosses grow in the crevices of the granite or other rocks, where moisture collects; the accompanying blue-green lichen spread out on the rock surfaces.

This is indeed a local scene; the pictures above are all from the rock cut just off Gurley Street to the west of the Eastern Orthodox Church.

When I was a high school biology student, mosses and lichen occupied a position in the botanical scheme of things just below the ferns, which in turn were just below the flowering plants, as measured in terms of biological complexity. Things are not so simple these days. Per the Arizona State University lichen site, lichens are a partnership between a fungus and either a green algae or a blue-green bacteria.

Lichen are tough customers, too. A sample sent out and exposed to space for over two weeks turned dormant and did not metabolize, but once returned to Earth, resumed normal activity and its DNA appeared not to have been damaged, according to a report in New Scientist, which noted that lichens have a tough mineral coating that could shield them from UV rays. They are also made from individual organisms layered on top of one another, so outer layers may provide protection for underlying cells. The organisms have already been shown to be capable of withstand high levels of UV radiation on Earth.

I don't have much exposed granite in up my hill, but lichen is quite happy growing on oak tree trunks and those stout mountain mahogany stems (above, below). Our common blue-green lichen is just one of 1400 species found in the Arizona/SoCalif/Sonora region.

When conditions are right (meaning very moist), lichen form fruiting bodies -- those round holes above -- which launch spores to spread the organism afield.

This pine tree trunk over at the Gurley Street site is covered with a yellow lichen; I do not know if this is a different species or actually the blue-green form that has died.


Steve said...

The shots with the green are very nice. We have more moss and lichen this year, due to all of the rain we've had.

azlaydey said...

I love lichen covered rocks............ I also had nice mushrooms growing in July.

Granny J said...

steve -- that's obviously our rain you've been getting there in Bavaria!

lady -- I had those, too, that week that we actually got decent rains.

Kathleen said...

Oh, it would be nice to have that much rain! Great photos =) And I enjoyed reading the information, too.

Granny J said...

frame -- speaking of info, I should have also noted that the crust formed on undisturbed desert floor is also a lichen.

Meggie said...

Julie, what a fabulous post! I love lichens, in all their forms & colours. I also love mosses, & cannot banish them from my garden, as Gom tries to do.

Granny J said...

meggie -- would that I had some moss in my garden. Here in dry Arizona, the mosses only become lush in the raing season . Unfortunately, our usual summer rainy season has been a bust this year.

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