The sun is not just essential but has a very critical and powerful role in our biosphere. If there were no sun, there would be no life, either plant or animal. Life on Earth depends on both direct and indirect sunlight to survive. We are indebted to the sun for every minute of life from one day to the next. How often do we even think of that? And, yet, the sun is a long way away, all of 93 million miles, so they tell us. It must be very powerful to give us heat and the right kinds of rays from that far away to keep us healthy both physically and emotionally. Scientists tell us that the sun is so powerful that if one part of it, the size of a pinhead, were placed within 100 miles of one of us it would kill us. I prefer that the sun keep its distance.
The sun, as a matter of fact, can keep its distance in both being not too close and, yes, not too far away either. Now plants, to some degree, control the effect of the warmth and light they get from the sun by turning, like sunflowers, to the sun, folding their leaves, closing pores and so on. Humans and animals can seek shade, get out in the sun and benefit from automatic physical controls.
However, none of these would be of much help if Earth were to vary by one very small fraction in its distance from the sun. If the sun were slightly farther away we would freeze to death and if it was a fraction closer we would roast to death. It is of considerable benefit, to us and all life, that the orbits of the sun, Earth and other planets stay precisely in the same path.
Much is written about the sun and how much it means to mankind and also to all forms of life. “Truly the light is sweet, And it is pleasant for the eyes to behold the sun.” (Ecclesiastes 11:7, New King James Version) Many plants are phototropic, turning to the light and to the sun. In evening, some species face the setting sun but turn, the following morning, to face its warming and life-giving rays. The sunrays warm up plants and provide essential rays that enable plants’ life processes to go on from spring’s leaf emergence to autumn’s leaf falling. Billions of leaves, “solar panels”, spread their blades in the spring to become food factories for the plant, hence providing firsthand nutrition for herbivores and to those of us who choose to be first-order consumers. How many leaves does a tree have ?
A very large tree might have 250,000 leaves. Now, spreading them on the ground one layer deep (if that were possible) they would cover just under 14,000 square feet if each leaf had eight square inches of surface. That is a very large solar panel array. (Six electrical energy solar panels might cover 90 square feet.) That is for a broad-leaved tree. A coniferous tree has leaves too. We say they have needles but actually coniferous trees in this area are needle-leaved trees. (Spruce leaves feel like needles.) Needle leaves are very efficient solar panels. Individually, they have a very small area but collectively they more than totally shade the ground. As much as leaves are solar panels, flowers are solar collectors and sun catchers.
One very striking flower sun catcher is the Ozark sun drop. Its bright yellow evening primrose blooms may reach as many as six inches in diameter, a truly magnificent yellow saucer shape that can cheer any heart, especially in the afternoon and evening, hence the name evening primrose. Sun catchers come in many different shapes, sizes and colors and designs to suit the need. I think of alpine lanterns (Selene uralensis) found at high elevations in our Purcell Mountains. The major portion of the bloom is a bladder, a large round compartment, functioning like a miniature greenhouse or solarium housing the reproductive parts of the flower. The walls of this little greenhouse are opaque, but the sun’s warmth still gets through. This little greenhouse shelters the developing seeds from excessive cold and drying winds.
A very small flower sun catcher is the scarlet pimpernel, a half-inch brick red five-petalled flower. It is phototropic, closing when shaded by clouds. Because of that, it has also been called poor man’s weather glass. A few plant names reflect the connection they have with the sun and its energy — sunflower, sundew and suncress. Many others are sunlight yellow.
Plants feed the body. “Flowers feed the soul,” said Mohammed.
Ed McMackin is a biologist by profession but a naturalist and hiker by nature. He can be reached at 250-866-5747.