Sunflower
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| A field of Sunflowers in North Carolina. |
Sunflower is the common name for any of the species belonging to the taxonomic genus Helianthus. Named for its large sun-like composite flower, growing from three to six inches in width with some wild species growing one foot in width. The garden giant also has a stem that can grow from three to twelve feet high.
The sunflower is worthy in both economical forms and decorative forms. The leaves can be used as feed for different livestock. The flowers of the plant can produce a yellow dye that is usable. The sunflower is commonly known for the seeds it produces that are both edible and contain oil.[1] Many people enjoy the sunflower because it adds a splash of bright summer color to their gardens as well as produce a healthy snack. [2]
Contents
Anatomy
The sunflower is a monoecious plant (having both male and female flowers on the plant at the same time). [3] This genus of flower has both perennial and annual species. Different varieties of sunflowers, range from fifty to five hundred centimeters in height. In other words, it can grow up to twelve feet tall, and the head can grow up to three inches wide. [4] Normally the stems tend to be unbranched. The length of the stem is decided by the internodes. An internode is a portion of stem between the nodes. [5] The first layer of leaves on the head of the plant, are always opposite; although, in some varieties they become alternate. Typically the leaves are petiolate and three nerved. To be petiolate means to have a petiole, the stalk of a leaf, which attaches the blade to the stem. The shape of the leaf varies from linear to ovate and tend to be whole or serrated. [6] The sunflower has a bit of a rough-hairy attribute that is common throughout all the species. The rough hair serve two purposes: (1) to prevent plant-eating animals from devouring itself and (2) to store water in the plant by restricting evaporation. [7] The sunflower is an annual broadleaf plant with a tough taproot.
Helianthus annus is a part of the Asteraceae family; although it is considered a composite flower. A composite flower is one where the head of the flower is not a single flower. Instead it is made up of about a hundred smaller single flowers. Each one of these small individual flowers produces their own single seed. This seed would be located in the achene, which is also known as the seed hull. The petals that a sunflower has are actually sterile ray flowers. A plant that has sterile ray flowers means that each petal on the head of the flower is it's own individual flower. While the flowers on the actual head of the sunflower produce seeds, these sterile flowers were created to allure insects. [8]
Reproduction
The sunflower reproduces sexually through the method of pollination. [9] On one individual flower, the sunflower contains both the female and male sex organs. On the disk of the sunflower, if looked at closely, one will be able to see a five pointed, fused corolla. This is actually five petals commixed together to make a whole corolla. Found in the center of each corolla, are both the male and female reproductive organs. The anther which contains the pollen, besets the style of the pistil. Then as the style progresses to grow, the pollen is propelled out. This is where the insects, allured by the petals, come find pollen. Once found by the insects, the pollen is picked up and moved to other sunflowers. Then when the style is completely done growing and the pollen is all gone, the style becomes disclosed and waits for pollen left from insects from another flower. [10]
Typically, sunflowers tend to be self sterile. But for a sunflower to produce seeds, it needs pollen from a different sunflower. This is also known as cross-breeding, or in this case, cross-pollination. Occasionally, a sunflower can self-pollinate. Self-pollination produces an inbred line which, when bred with a separate inbred line, will result in a hybrid flower. [11] When signs of Autumn are near, each individual flower on the head will produce a seed. [12] But before the flower sets to seed, the head must open. Once it begins to open, changes begin to happen. Once the head is fully opened, one will be able to see that the individual disk flowers are not yet developed. The head also appears slightly flat. Beginning with the outer edge of the head, the the ring after all the petals, happen to be the male organs: the anthers that produce pollen. The anthers will be leaning in towards the center of the head. After the ring of anthers, come some of the female parts: the style branches. After pollen from another flower has been transported onto the style branches, the disk will begin to shrivel and dry up until it falls. In doing so, it reveals the achenes while the seeds are fully developing. The head of the flower often tilts towards the ground because of the weight of all the seeds on the disk. [13]
Ecology
Today, the sunflower grows in vast semi-arid regions of the world in countries varying from Argentina to Canada and from Central Africa all the way into the Soviet Union. In America, they can be found anywhere from the great northern plains of both North and South Dakota and all the way down to the very southern end of Texas.[14] The sunflower was one of the first crops that originated from North America. Although other species were originated in the fertile crescent areas of Asia, and both Central and South America. Some researchers believe that the traveling Native Americans might have carried some Sunflowers with them, dropping seeds as they journeyed south to east across the country. Some of the first European explorers first found the sunflower growing in areas from Southern Canada to Northern Mexico. [15]
- Temperature
Sunflowers have high tolerance levels and can grow in both high and low temperatures; although it is more liberal to colder temperatures. The seeds can germinate at about 39 degrees F. But in order for the seeds to have adequate germination, temperatures of at least 46 to 50 degrees F are needed. In the early stages of the germinating process, the cold weather has no effect on the seeds. [16] The best temperatures for overall growth are from around 70-78 degrees F. Temperatures in wider range such as 64 to 91 degrees F would not have a healthy effect on the plant growth. Also, temperatures that are extremely high tend to reduce oil percentages, germination, and seed fill. [17]
- Soil
Sunflowers can grow in a wide variety of different areas/grounds. Locations range from different soil types, sands, and clay. The demand for sunflower crops is not as strong as would be for plants such as potatoes or corn. Nitrogen is typically the first limiting factor for plants. In order for proper plant growth, high levels of macronutrients are required in the soil. Because the sunflower contains a huge amount of these ingredients, growing in soil lacking these ingredients tends to turn out all right. The amount of macronutrients tends to vary in different species. In most cases, the macronutrients are returned to the soil through the stover. Proper growth also requires a good amount of soil drainage; its flooding tolerance is about equal to other plants. Without proper draining, the plant would drown. [18]
Sunflower Seeds
Sunflower seeds are also known as achenes. The actual outside part of the seed is called the hull. This part is not edible, however the remaining part inside is. This part is known as the sunflower kernel. [19] The seeds tend to be distinguished by the pattern on the hull. If the hull is completely black, then they are known as "black oil sunflower seeds". But if they are black with white stripes, these are known as the "stripers". These have less sunflower oil than the black seeds, which are usually pressed into the oil. [20]One of the most common uses are sunflower fruits, which are sold as a snack food, especially in the United States, Europe, and China. They are also used as bird food. One of the new uses for sunflower seeds is in the production of bio-diesel. In the past, olive products have been used in bio-diesel, but sunflower seeds are cheaper and in greater quantity. Sunflower seeds consist of 36-42% oil and 38% protein meal. Agricultural experts from Brazil are studying how to change sunflowers into oil in a cost-effective manner. Researchers say that if this project is successful, biofuel will become relatively inexpensive. [21]
Sunflower Seeds used as mood stabilizers?
Studies have taken place and researchers have found that different kinds of nuts and seeds are able to boost not only brainpower, but elevate moods as well. The nuts vary from the most common: cashews, walnuts, and almonds, to the most exotic. Studies show that it gives you the ability to think clearer and create a happiness almost unimaginable. Certain nuts and flax seeds can serve as another option for antidepressants. Projessor James Duke, found that several different kinds of seeds and nuts hold tryptophan. Tryptophan is a crucial amino acid that the brain changes to serotonin. Serotonin is active as a neutrotransmitter, stimulator of the smooth muscles, and regulates the body's cyclic processes; it is also active in vasoconstriction. [22] He continued to research and discover, finding that sunflower seeds contain a great amount of tryptophan. This creates a healthy option to allay mild depression and insomnia. Researchers also found that sunflower seeds are high in thiamine, which is a substantial B vitamin and helps with memory and cognitive function. They suggested if you're feeling down, rather than popping pills, pop some seeds and nuts and you'll notice a difference. [23]
Sunflower Gallery
Common Sunflower
Helianthus annuus
Sunflower's Macro
Helianthus annuus
Common Sunflower
Helianthus annuus
Sunflower seeds from the head of a sunflower.
Bremerhaven, Germany.
References
- Sunflower Ohio State University
- Sunflower Wikipedia
- Sunflowers Answers Corporation
- The Biology of Helianthus annuus L. www.agbios.com
- Sunflower Breeding & Biology www.geocities.com/sunflower
- National Sunflower Association www.sunflowernsa.com
- Sunflower www.hort.purdue.edu
- Sunflower www.gpnc.org
- Glossary www.swcoloradowildflowers.com
- Sexual Reproduction in Garden Flowers www.myhrsb.com
- Biofuel from Sunflowers www.agribusinessweek.com
- Sunflower name Search www.plants.usda.gov
- Sunflower www.encyclopedia.org
- Serotonin www.answers.com
- Seeds and nuts...mood stabilizers www.naturalnews.com
