flower

Sunflowers (Helianthus annuus).

Sunflowers are usually tall annuals, that grow to a height of20–154 in. The rough and hairy stem is branched in the upper part in wild plants but is usually unbranched in domesticated cultivars. During growth, sunflowers tilt during the day to face the sun, but stop once they begin blooming. This tracking of the sun in young sunflower heads is called heliotropism. By the time they are mature, sunflowers generally face east. Sunflowers are grown commercially for their seeds and oil from seeds.

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