Gardening Topic for October 2008
Looking at and Liking Lichens

Provided by the Western Massachusetts Master Gardener Association
www.wmassmastergardeners.org.

When the first snowflakes come and when the ice recedes, lichens light up the rocks and trees. They have been there all along but are often missed when the eye is taken by larger and more complex plants. The lichens, and mosses, especially when viewed with a hand lens, should not be ignored by anyone who loves to garden. The same delight in forms and color that draw us to a beautiful copper beech tree or peony will be felt with closer observation of these tiny plants.

Lichens are a true example of ultimate cooperation in order to live well: an algae, the simplest in structure of the chlorophyll-bearing plant cells, and a fungus, a non-chlorophyll-bearing but walled cell that just happens to grow in a netlike fashion, join to survive. The fungus determines the shape of the lichen. The alga, or algae (as there are examples where two different chlorophyll-bearing species live with the fungus in a ménage-a-trois), has the role of photosynthesis. The chlorophyll in the alga allows sugar, the food of life, to be made while the acid-producing fungus dissolves the surface on which the lichen grows for minerals and other nutrients. Some lichens that include a blue-green algae partner are also nitrogen fixers. With moisture, many different genera can be found during a late fall or early spring walk, the times when most gardeners are least likely to be outside hoeing and weeding.

The presence of lichens is a healthy sign that air is pure and the world is in balance. They are indicator organisms for air pollution, especially to sulfur dioxide and ozone. Most prefer a shaded environment, for like mosses, a sunburn can be deadly, but again, species have learned to adapt in cooperative fashion by hunkering down in the fibrils of the encompassing fungal threads. It is the fungus partner that determines the shape of the lichen and a viewer will often see cup-like fruiting bodies on many that look like familiar big cup mushrooms. In any basic biology text the lichens will be cited as an example of a true mutual symbiosis and also the first life in bare rock succession. What we see on our New England walks is a group of plants that could be displayed in the Guggenheim Museum. They are often the focus of nature photography. Elliot Porter's work shows they did not miss the objectivity of his eye or camera lens. Lichen colors are muted but one of the reasons for looking at them in off-seasons is that they almost glow along the roadsides on trees and old stone walls. Grab your hand lens and look closer. It is interesting to note that the dyes used by Scots to create their tweed wools and the familiar litmus dye, the acid-base indicator paper and so familiar to science students, are both derived from lichens.

Form determines classification of lichens that can be a taxonomic trip most of us do not want to make but it is satisfying to identify whether the lichen is crustose, foliose or fruticose. The crustose lichens will not have any leafy quality and will grow flat on a surface. They are the ones seen on the rocks of ocean cliffs surviving salt spray or what looks like paint splatters on our rock walls and gravestones. They might show a bumpy center with a hand lens. The foliose lichens have leafy lobes. Gray-green orbs of Parmelia truly glow after a wet period. Hard to miss with its rather big-for-a-lichen, blackish, strange flaps are members of the Umbilicaria genus, known as rock tripe. They are edible. Fruticose lichens are the ones most likely to be collected for a terrarium. British Soldiers, Pixie Cups, and Reindeer Moss (all Cladonia) have all let the fungus partner build the MacMansions of the lichen world. These are the lichens that extend into fantasy shapes and into your imagination.

The fruiting bodies of lichens, viewed in a quiet moment with a hand lens or even the naked eye, cannot help but stimulate the artist within us all. But it is also the importance of lichens in the scheme of keeping the earth in balance that is critical to our giving them attention. If there are no lichens, the air is not healthy. The attention made in noticing them is a bit like learning a new word and then seeing it in print again and again. They will enrich your experience even if your summer garden is the ultimate place of joy. In the bleakness of late fall and early spring lichens can give you a similar high.

Lichen
Xanthoria parietina

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Provided by the Western Massachusetts Master Gardener Association
www.wmassmastergardeners.org