Fungi and Algae = Lichens
Horticulture Hotline 04/30/24
By Bill Lamson-Scribner
When I was a kid, I learned that rocks became soil. After many years, that was my memory of the process and not much of the details. A while back, I was talking to a friend of mine that is a naturalist and he works mainly in Alaska. We were talking about groovy, cool things that naturalist and horticulturalist talk about when given the opportunity. This evening, we were talking about mountains, glaciers, and soils.
The conversation about rocks becoming soil was of particular interest to me, since I spend most of my adult life dealing with soil. When he mentioned lichens growing on rocks was the first step, he really had my attention. I have written and talked about lichens many, many times, usually as they relate to plants:
It sounds like you have lichens. Lichens are grayish-green organisms that are a cross between fungi and algae. They make their own food and collect their own water and minerals, so technically they do not harm the plant or tree on which they are growing. They are a sign that the tree or shrub is not flourishing. Lichens do not hurt what they are growing on – they are a sign that what they are growing on is hurting!
Since lichens manufacture their own food through photosynthesis, they need sunlight to carry on photosynthesis. A healthy actively growing plant or tree is the best defense against lichens. If the tree or shrub has a thick canopy, the lichens will not survive since they need sunlight to manufacture their food. Culturally, the plant must be planted in an area that provides the conditions that the plant can thrive, so it produces a dense canopy that will shade out the lichens. Proper fertilization based on soil tests and proper pruning will help to keep the canopy thick. Think of trying to grow grass under the thick canopy of a tree – the grass needs sunlight for photosynthesis like the lichens and will not grow in the dense shade.
Lichens will grow on rocks, plants, the side of your house, and anywhere else that they get sun and water. When lichens grow on rocks, dirt and dust begins to collect on its scaly growth. A random seed might get in that dirt and dust and begin to grow.
When hiking in the foothills above Clemson, I would see little stunted trees growing in the rocks. I always called them nature’s bonsai trees. These small trees growing out of rocks, would collect leaves, small branches, and other organic matter coming down the mountain. Roots from the plants find tiny cracks in the rock. As the roots grow thicker, they could crack the rock. Water would also get into these fissures and freeze, expand, and crack the rock.
In Alaska, snow melt running down the side of mountains plays a huge part in turning rock into soil. A drop of water, a stream, a river, a glacier…
After a few chicken wings, lichens start the whole process. Depending on the minerals that make up the rock that is broken down to make your soil, will determine the type of soil you will have. That is why soil testing is so important.
Soil Tests, pots, potting soil, soil moist, neem oil, horticultural oil, Cotton Burr Compost, gift certificates, rodent control, roach control, mole crickets, fire ants, moles, pruning (azaleas and camellias), grass coming out of dormancy are just a few things that seem very popular right now.
Always read, understand, and follow product label. The product label is a Federal Law.
Bill Lamson-Scribner can be reached during the week at Possum’s Landscape and Pest Control Supply. Possum’s has three locations 481 Long Point Rd in Mt. Pleasant (971-9601), 3325 Business Circle in North Charleston (760-2600), or 606 Dupont Rd, in Charleston (766-1511). Bring your questions to a Possum’s location, or visit us at possumsupply.com. You can also call in your questions to “The Garden Clinic”, Saturdays from 10:00 AM to 11:00 AM, or listen to the replay of Saturday’s show, Sundays from 11:00 to noon on 1250 WTMA (The Big Talker). The Horticulture Hotline is available 24 / 7 at possumsupply.com.
