January 5, 2014

Booking time in winter to catch up on reading list

Throughout the year I collect new books and there is never enough time to dig into them during the summer and fall. In winter I savor the time to compare my photos with my field guides and investigate questions I haven’t yet answered.

My favorite new field guide is “Lichens of the North Woods” by Joe Walewski, a handy, small field guide to 111 northern lichens. Although the author is from Finland, Minn., and the book’s primary area is the Great Lakes region, the lichen species included are nearly all found in the Adirondacks.

Lichens make up for their obscurity with names like Candleflame, Tree Jelly, Methuselah’s Beard, Crumpled Rag and Yellow Specklebelly. This book prompted me to start training my eyes to notice more lichens and where they grow.

Lichens are not single organisms — they are a partnership of a fungus and an alga or cyanobacteria. Although the fungus and the alga or cyanobacteria might exist by itself in nature, many have become completely dependent on each other and do not exist as independent individuals. The University of California Museum of Paleontology refers to lichen as “an alliance between kingdoms.”

In the partnership the alga has the ability to make food through photosynthesis and the fungus provides the protection of structure and shade. Lichens spread when small pieces break off — each piece contains both parts of the organism. Although they can begin growing right away lichens grow extremely slowly. They have a remarkable ability to withstand extremes of drought and temperature and resume growth. 

Lichens grow on the ground, on rocks and on trees. Some species grow on more than one substrate, but generally the first step of lichen identification is to note the substrate. Texture, moisture retention and chemistry determine which lichens favor which surfaces. 

The second step of identification is to determine a lichen’s shape. Most are one of three basic shapes: crustose, fruticose or foliose. Walewski keeps the explanations of each shape simple: “Crustose lichens look like spray paint”; “Foliose lichens look like leafy growths divided by lobes”; and “Fruticose lichens are literally bushy or shrubby growths.”

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