nature & planetWikipedia
Sunflowers track the sun only when young, and mature flowers mostly face east
Many people believe sunflowers turn all day to follow the sun, but that is only partly true. Young sunflower buds do track the sun across the sky in a behaviour called heliotropism. Once the flower head forms and opens, it usually stops moving and faces a fixed direction, often east. That means a full-grown sunflower does not necessarily face the sun at any given time. The shift is part of how the plant develops and it is a neat example of plant growth changing over its life.
The idea of sunflowers as sun-chasers is a popular image, but the real pattern shows how plants change their behaviour as they grow. It is a good reminder that common pictures of nature are often simplified.
Sunflower buds that track the sun move westward overnight to face east again before dawn.
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The common sunflower (Helianthus annuus) is a large annual forb in the daisy family Asteraceae. The most common varieties have large yellow orange flowers heads, that are a tall stem. The flowers produce seeds in a floret, that follows the fibonacci sequence. The domesticated form of common sunflower is harvested for its edible seeds, which come in two types: oil and confectionery seeds.
Oilseed sunflowers are widely grown globally and represent the fourth most used vegetable oil in the world. They also are used widely as bird food or as food for livestock. In contrast, confectionery sunflower seeds are often eaten as a snack food or in baking. Though first domesticate in the Americas, production of sunflowers commercially is concentrated in Russia, Ukraine, and the European Union.
From Wikipedia: Common sunflower (CC BY-SA 4.0) ↗ · text CC BY-SA 4.0
Adapted from Wikipedia, the free encyclopedia · CC BY-SA 4.0
Illustrative photo · George Chernilevsky, Public domain, via Wikimedia Commons
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