Heliotropism, Sunflowers and Moonflowers

If walls could talk of the wonderous beauty that surrounds them, that changes with the seasons, and brings us sunflowers in the summertime. Although encased in stone, mortar and concrete, we rather look forward to seeing the world in beautiful shades of glorious wonder. I would speak of the lovely flowers which share a joyful smile with me, especially in the bright sunshine when the world comes alive with much excitement, children playing, beaches filled with happy faces, and birds of every species cawing delightfully overhead.

I recently had the chance to converse with the beautiful yellow Sunflower and her friend the coy Moonflower. They had this very informative story to tell about their history and many uses. It was quite eye opening.

The common sunflower (Helianthus annuus) is a large annual flower which can be found growing almost anywhere. It is commonly grown as a crop for its edible oily seeds. Apart from cooking oil production, sunflowers are also used as livestock forage (as a ready meal or stored for winter consumption), as bird food, in some industrial applications, and as decorations in domestic gardens. The wild sunflower is a widely branched annual plant with many flower heads, the domestic variety often possesses only a single large inflorescence (flower head) atop an unbranched stem.

The binomial name Helianthus annuus is derived from the Greek Helios 'sun' and anthos 'flower', while the epithet annuus means 'annual' in Latin.

Did you know that it's not only their appearance that gives sunflowers their common name. As young plants, sunflowers actually 'follow the sun' during part of the day because of a process called heliotropism.

Some sunflower species are perennials, but it is the common (annual) sunflower that exhibits heliotropism. Sunflowers not only face each other or orient in random directions. There is directional uniformity among plants of similar age. Before their flowers form and are pollinated, young sunflower plants face the sun at dawn, and follow the suns movement as it moves across the sky. The internal clock of their circadian rhythm reverses their movement after the sun goes down, and they once again face the eastern sky until the sun rises the following morning. When they mature, they remain in a fixed position facing east which allows for rapid warming in the mornings.

Intricate functioning of plants such as sunflowers, which exhibit heliotropism, involve more than one mechanism which allows them to move. Specialized cells in a structure called the 'pulvinus', are located at the base of leaves or flower buds. These cells contain motor cells that fascilitate the plant's movement as it tracks the sun. The water within the pulvinus creates 'turgor pressure', which enlarges or shrinks pulvinus cells, and triggers movement that includes bending of the stems.

Benefits of sunflower seeds and oils.

Sunflower "whole seed" (fruit) are sold as a snack food, raw or after roasting in ovens, with or without salt and/or seasonings added. Sunflowers can be processed into a peanut butter alternative, sunflower butter. It is also sold as food for birds and can be used directly in cooking and salads. Native Americans had multiple uses for sunflowers in the past, such as in bread, medical ointments, dyes and body paints.

Sunflower oil, extracted from the seeds, is used for cooking, and to produce margarine and biodiesel, as it is cheaper than olive oil. A range of sunflower varieties exist with differing fatty acid compositions; some "high-oleic" types contain a higher level of monounsaturated fats in their oil than even olive oil. The oil is also sometimes used in soap. After World War I, during the Russian Civil War, people in Ukraine used sunflower seed oil in lamps as a substitute for kerosene due to shortages. The light from such a lamp has been described as "miserable" and "smoky."

The cake remaining after the seeds have been processed for oil is used as a livestock feed. Some recently developed cultivated varieties have drooping heads. These varieties are less attractive to gardeners growing the flowers as ornamental plants, but appeal to farmers, because they reduce bird damage and losses from some plant diseases. Sunflowers also produce latex, and are the subject of experiments to improve their suitability as an alternative crop for producing hypoallergenic rubber.

Ukraine is the largest supplier of sunflower oil and seeds in the world, it is also their national flower. The country is covered in fields of sunflowers due to the importation of the seeds from North America in the 1800's.

Sunflowers can deplete the nutrient from the soil if found growing among other food plant and lead to a reduction in yield of the crop.

Uses as soil decontaminant

Sunflowers can be used in phytoremediation to extract toxic ingredients from soil, such as lead, arsenic and uranium, and used in rhizofiltration to neutralize radionuclides and other toxic ingredients and harmful bacteria from water. They were used to remove caesium-137 and strontium-90 from a nearby pond after the Chernobyl disaster, and a similar campaign was mounted in response to the Fukushima Daiichi nuclear disaster.

The African moonflowers do the same, but at night while facing Mecca. Also known as:

Ipomoea alba, sometimes called the tropical white morning-glory or moonflower or moon vine, is a species of night-blooming morning glory, native to tropical and subtropical regions of North and South America, from Argentina to northern Mexico, Arizona, Florida and the West Indies.

The flowers are fragrant, white or pink, and large, 8–14 cm diameter. The flowers open quickly in the evening and last through the night, remaining open until touched by the morning dew. On overcast days, the blossoms may remain open for longer. The flowers also tend to remain open longer during cool temperatures - which may also cause the segments to snag or tear as they open.

The name moonflower derives from their blooming in the evening and their being round in shape like a full moon.

Humans use Ipomoea for their content of medical and psychoactive compounds, mainly alkaloids. Some species are renowned for their properties in folk medicine and herbalism.

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