Common sunflower

The common sunflower is a species of sunflower known by the scientific name Helianthus annuus. They are best known for their seeds, which are sold as a snack. Sunflower seeds can also be processed into a peanut butter alternative called sunflower butter. It is also sold as food for birds and can be used in cooking and salads. American Indians had multiple uses for sunflowers in the past, such as in bread, medical ointments, dyes and body paints.

Body Design
The common sunflower has an upright rough-hairy stem, reaching typical heights of 9.8 ft. The tallest sunflower on record achieved 30.1 ft tall. Sunflower leaves are broad, rough and mostly alternate. What is often called the "flower" of the sunflower is actually a called the "flower head" or false flower of numerous small individual five-petaled flowers. The outer flowers, which resemble petals, are called ray flowers. Each "petal" consists of a ligule composed of fused petals of an uncorresponding ray flower. They are sexually sterile and may be yellow, red, orange, or other colors. The flowers in the center of the head are called disk flowers. These mature into seeds.

The disk flowers are arranged spirally. Generally, each stem is oriented toward the next by approximately 137.5 degrees producing a pattern of interconnecting spirals, where the number of left spirals and the number of right spirals are successive Fibonacci numbers. Typically, there are 34 spirals in one direction and 55 in the other; however, in a very large sunflower head there could be as much as 89 in one direction and 144 in the other This pattern produces the most efficient way of packing seeds mathematically possible within the flower head.

Life Cycle
Once the sunflower has flowered, usually in summer, it produces a sweet pollen mixture that lures bees and other insects. When the bees arrive, they get their feet wet with the pollen as they drink the plant’s nectar. The plant relies on the sperm-producing pollen coming into contact with the egg-containing stigma (the part of the pistil where pollen germinates). The yellow pollen is transferred from the insect’s hairy legs to the stigma. This is the first step in sunflower reproduction. Once the pollen is forced down the stigma, it releases sperm into the stigma. An available egg receives the sperm, and the egg is fertilized with a meat-bearing seed. The pollen can belong to the original plant or may come from another sunflower. Self-pollination is a mechanism that this flower uses to stay alive. On the occasion where the stigma receives no pollen, the stigma will twist and wrap itself around its own pollen. Seeds created by self-pollination will only produce flowers that look like the original plant, so no hybrids will be made.

Ecology
The sunflower habitat consists of prairies and dry, open areas. It is sometimes a weed in cultivated fields and pastures. It grows best in sunny, moist, or disturbed areas. The sunflower is tolerant of high and low temperatures, although more tolerant to low temperatures with the optimum temperature range being 70-78 degrees Fahrenheit. Other organisms that live within the habitat of the common sunflower include: prairie grasses, wild flowers, small animals like rodents and snakes and a large variety of insects. Sunflowers fit into their ecological niche by growing where resources are abundant, yet where disease will not affect them.

Cultivation and Uses
Sunflowers grow best when they get a ton of sunlight. They grow best in fertile, moist, well-drained soil with heavy mulch. In commercial planting, seeds are planted 1.48 ft apart and 0.98 in deep. Sunflower seeds are sold as a snack, 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 in cooking and salads. American Indians had multiple uses for sunflowers in the past, such as in bread, medical ointments, dyes and body paints.

However, for commercial farmers growing primary crops, the sunflower, like any other unwanted plant, is often considered a weed. Especially in the Midwestern US, wild species are often found in corn and soybean fields and can have a negative impact on yields.