Thursday, June 18, 2015

Looking at Lichens

There are grand panoramas to be had on hands and knees at Halibut Point, especially on misty days.

Two crustose lichens, commingled
I sometimes fantasize about being sub-Lilliputian, ant-size, to wander through the microcosm growing on bare ledge, looking up at and admiring botanical creations that could stimulate other-worldly imaginations at George Lucas's film studio.

A lichen fruiting
Savannahs and multi-canopied forests would stretch to the horizon, composed of towering plants that in my ordinary life escape notice under foot.

As an obtainable but definitely second-best passport to the Terrain of the Tiny I coax my camera into macro focus and consult new guidebooks. The predominant vegetation consists of mosses and lichens.
Lichens subordinate, mosses fruiting
Up close, mosses are a weird-looking set but they're definitely plants. Generally they depend on at least rudimentary soil and water supplies to prosper. Some kinds can make it at the margins of the ledge, or in shallow depressions. In the photo above two types of mosses are fruiting.

Mosses subordinate, lichens fruiting
You might think of  a lichens as a partnership formed by two different plant groups combining to make a living where no single entity could survive. In this sense a lichen is not a plant per se. I called on Martha Finta to shed light on how this works.
Martha Finta examining lichens on an oak tree
As we head into Halibut Point State Park Martha points out four different lichens growing on a tree we. The lichens find anchorage on the bark but otherwise seem to draw no sustenance from the host. Not a hint of the parasite about them.

Martha refers to the botanical complexity of lichens as 'mutualism.' A certain group of fungi - which have no chlorophyll and cannot directly convert the sun's energy into organic energy - has gained the ability to enmesh certain green-celled algae or cyanobacteria to draw on their capability to photosynthesize. The fungal component adds sponginess as a water reservoir for the pair, and no doubt other biochemical benefits.
These lichen arrangements have developed many different forms, and the ability to reproduce as a unit. Their life history makes very interesting investigation. Like Martha you can go on field trips by joining the Friends of Harvard University's Farlow Library and Herbarium of Cryptogamic Botany - the lichen, moss, and fungus people.
Lichens on ledge
With a magnifying glass and field guide we start trying to identify diverse lichens in the Park. Some of the common names are Zen-like. The science is demanding, on the eye and on the tongue.

Lichens on concrete
Martha's discovery tour included moments like these:

"That's not the 'maple dust lichen,' but another one. I wonder if it's not this.... Nope, not nine-tenths of a millimeter. Did it look like this under the glass?... Oh, it's this family. Dimelaena oreina. It could be confused with another one. Hah!...Oh great. 'Golden moonglow lichen.' But it doesn't really have yellowish lobes. I saw some black dots but I don't know if they're level with the surface."
Lichens on granite bench
"I think it could be porpidia, but it's nothing concentric. The ones I have seen of porpidia are usually crustose like this, very fine."

"This is one with the black discs. No, wait, they're brown discs. We have a small mystery, at least for the moment. Probably it's an aspicilia. Here we go! 'Cumberland rock shield,' Xanthoparmelia cumberlandia.

I ask Martha what keeps her at it. "What's the draw?"

Martha - "It's like being one with your surroundings, to know what it is. It goes hand in hand with Nature. It's instinctual."
Me - "You had to take a bus to come over here."
Martha - "You called. Someone wants to learn more about it. Let's see what happens. It's an adventure."
Rock surface
Rock surface, detail
Recommended reading
Lichens of the North Woods, by Joe Walewski
Common Lichens of Northeastern North America: A Field Guide, by Troy McMullin and Frances Anderson
The Granite Landscape, by Tom Wessels

1 comment:

  1. What a marvellous blog post. I am fascinated by lichens and mosses. Thanks for this.