How to Describe the Parts of a Sunflower

The sunflower is a special type of flower because it is considered compound. That means that what we consider a single flower is actually more than a thousand small flowers called "florets." Because sunflowers are large and easy to grow, they are a perfect flower to study close-up without a microscope. Children enjoy growing these cheerful flowers and can learn from cutting the flower open so the parts can be identified and named. Being able to describe the parts of a sunflower is an excellent demonstration of botanical skill.

Things You'll Need
Live sunflower that has bloomed
Sharp knife
Magnifying glass (optional)

Instructions

1. Carefully cut your sunflower so that about 10 inches of stalk remains below the flower head. Cut your sunflower in half so that you can see the inside of the stalk below the flower head. Keep the other half of the sunflower head.

2. Identify the stalk of the plant and refer to it as a "peduncle." Call the whole flower head an "inflorescence" and explain that an inflorescence is a group of flowers in this case, and that the sunflower head is composed of many smaller flowers. Point to the white interior of the peduncle and observe the pith, as well as the domed receptacle that forms the top of the inflorescence stalk.

3. Observe the green leaf-like formations on the outside of the flower head; they are the "bract." The bract appears between the stalk and the inflorescence.

4. Pluck one of the soft, yellow, orange or white petal-shaped forms above the bract and identify it as a "ray floret." Ray florets are sterile and attract pollinating insects, and surround the head of the sunflower plant.

5. Place the two halves of the sunflower together again. Notice the outer ray florets and how they are different from the "disk florets," which form the interior flowers of the plant. Study one cross section again, perhaps with a magnifying glass, and observe the differences between the disk florets in the center of the head, and those on the exterior of the head near the ray florets. The florets closest to the center are the youngest florets and may be immature. The immature florets have a long pod-like structure.

6. Move your magnifying glass toward the edge of the disk florets and observe the flowers in varying stages of fertilization. Florets that have begun to open send forth "anthers" that carry pollen, so you can track the development of a sunflower by the percentage of disk flowers that have produced anthers and have been fertilized.

7. Point out the fertilized florets closest to the ray florets. Once the florets are fertilized they appear as soft colorful tubes with tops that resemble a crown. As the living sunflowers mature you can continue to observe the pollination of the flower heads as the disk florets all gradually open.

Source: http://www.ehow.com/how_8591681_describe-parts-sunflower.html

Information on Sunflowers

Sunflowers are annual plants that are native to the Americas. Their stems can grow to more than 10 feet high, and their flower heads can reach nearly 12 inches in diameter. The scientific name for sunflowers is Helianthus annus. Many people refer to all of the plants in the genus Helianthus as sunflowers, but they are not true sunflowers, and some of them are actually perennial plants.

Description
The head of the sunflower is not one flower, it is a head that contains many small flowers that are packed together tightly. The outer florets on the head, called ray florets, can be orange, maroon, yellow, or other colors. The florets inside the head are called disc florets. Many people call the disc florets sunflower seeds, though they are truly not seeds but the plant's fruit.

History
The earliest recorded evidence of domesticated sunflowers dates back to 2600 BC in Mexico. The earliest evidence of domesticated sunflowers north of Mexico dates to 2300 BC in the area we know as Tennessee. The first European recorded to encounter the sunflower is Francisco Pizarro when he traveled to Peru. The Incas, the Otomi and Aztecs used the flower as the symbol of their sun god. By the 16th century, sunflower seeds were being shipped into Europe, as well as gold figurines of the flower. Sunflower oil became popular during the 18th century, especially among the Russian Orthodox Church, because it was a type of oil that was not prohibited from being used during Lent.

Uses
Roasted sunflower seeds are sold as snack foods. The seeds are also processed and used as an alternative, called sunbutter, to peanuts in peanut butter. The seeds are mixed with rye flour in many countries, particularly Germany, to make whole seed bread. Sunflowers can be used directly as salad toppings, in various food recipes and also as bird food. The oil from sunflower seeds can be extracted and used for cooking oil and to produce margarine and even biodiesel. The remains of the sunflower after the seeds have been extracted are often used as feed for livestock. Sunflowers are known for extracting toxic substances from the soil such as lead, uranium and arsenic. They were planted and used for this purpose after the Chernobyl disaster.

Growing
Commercial planters plant the seeds 1.5 feet apart and to a depth of one inch. Sunflowers grow best in full sun in well-drained soil rich with organic matter such as mulch. Home growers can plant them as they wish, either as individual plants or in groups.

Harvesting
Sunflower seeds should be harvested when most of the petals have fallen off of the plant head. To harvest, cut off the flower head, leaving a three- to four-inch stem. Hang the heads by their stems in an area that is well ventilated. As soon as the flower head has completely dried out, rub two flower heads together, and the seeds will pop out.

Source: http://www.ehow.com/about_5103780_information-sunflowers.html