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SunflowersHelianthus sp. Sunflowers are so named because of their "habit" of turning their flower heads to face directly into the sun; as well as for their big, yellow flowers, which somewhat resemble a simple sun. There are many individual species, with the most commonly known being Helianthus annus, which produces the seeds which sunflowers are known for. All sunflower species are herbaceous annuals with a fairly rigid, sometimes hairy, stalk, alternate leaves, and prominent yellow flower heads. Wild sunflowers average two to five feet in height with flower disks up to six inches across, while cultivated varieties can be up to ten feet high and have a flower disk up to a foot across. Native sunflowers are found across the western United States from the Mississippi River to the Pacific and from northern Mexico into southern Canada. They grow in a variety of soils and habitats, and do well in dry, hot conditions and in poor soils. Blooming typically begins in early summer, and continues into early fall. All varieties have a taproot that, depending on soil type and moisture conditions, can reach a foot or more deep. Many varieties appear to have a natural immunity to insect pests. Sunflowers were first cultivated over 3000 years ago by Native Americans, who selected plants based on the number and sizes of seeds produced. The plant was introduced into Europe, in the 16th century; while it is unknown exactly who first took sunflower plants to Europe, it was the Russians who first grew them commercially there. Russia still leads the world in commercial sunflower production, followed by Argentina, the United States, and Canada. Minnesota and the Dakotas are the leading sunflower producers in the U.S.; Manitoba is the leader in Canada.
The wild native sunflower (Helianthus annus) became the official flower of Kansas in 1923. Scientific Classification division Magnoliophyta |
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ROBINSON LIBRARY --> Science. --> Botany. --> Angiosperms (Flowering Plants).
--> Family Asteraceae (Asters). This page was last updated on 03/17/2011. |
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