In the field of horticulture there is a distinction made between deciduous and non-deciduous trees. Right now people in my part of the world are more conscious of deciduous trees: those that shed their leaves in the late fall. Soon, as the holiday season approaches, we will be paying more attention to non-deciduous trees, which we know primarily as evergreens.
Deciduous is a word from Latin which simply means “falling.” It fits.
The process of deciduous trees and shrubs dropping their leaves (in abundance where I live) is called abscission. It is the act of dropping leaves. Deciduous is a term that is also used to describe the way in which a deer will lose its antlers annually, or when a small child loses baby teeth. But the most common use of the word is when related to leaves falling from trees.
In New England the trees begin to change color to spectacular pieces of art in September or early October. It starts in the areas further north and slowly progresses southward, eventually affecting trees in the Middle Atlantic region and even the northern portion of the South. Other parts of the country see this beautiful transition, as well, but I’m prejudiced that it is most spectacular in New England. Maybe it’s the quaint towns, church steeples and meandering streams that make the difference.
There’s a range of mythology about what causes the leaves to turn colors and then drop to the ground. Many think it has to do with the amount of rain that has or hasn’t fallen, an erratic temperature pattern, or other characteristics of recent weather. The best science points out that it has to do with photosynthesis, which is related to the ability of the plant or tree to produce chlorophyll. The process is triggered by the shifting of the sun’s rays, which are particularly necessary for photosynthesis. As the amount of chlorophyll in the leaf diminishes, the other chemicals in the leaves which are already present are then permitted to demonstrate themselves, resulting in the changing of color. It is an amazing process, when you think of it. Just proof that all chemical processes are not invented by college-degreed humankind.
The various colors of the trees have to do with the specific chemicals that dwell within the leaves. There is some relationship to the changing days of weather patterns, in that warm days and cool nights stimulate the transition. Some trees have little or no residual, color-producing chemicals so the leaves simply fall when the stem is weakened by the process.
We who are house dwellers are “blessed” with the product of deciduous trees. Thousands upon thousands of leaves (depending upon the number of trees surrounding you) fall on the lawn, the driveway, and all over the roof of the house. Many hours are spent every fall in gathering the leaves and carting them off to dumps. We who live in condos are particularly thankful for contracted companies that take care of the process.
In days past, before we became more conscious of environmental issues, leaves were burned by the side of the street, sending dangerous fumes into the atmosphere. While I appreciate the change in practice in order to protect the atmosphere, I miss the smell of burning leaves. There’s nothing like it.
Photo Credit: Christopher and Amanda Elwell
Much of the scientific data is the result of a very good article on Wikipedia