Magical Sunflowers (not just a pretty face)

Huge stems and enormous brightly coloured flowers that follow the sun are only the tip of the attraction of sunflowers.

They are usually the first seeds our children grow in school, they are depicted as characters in children’s books and are a pronounced splash of colour in many vegetable gardens.
They represent ‘a happy smiling face’ to many people and stand to attention like soldiers when they guard our vegetable plots.

But hidden inside the intricate flower heads are secret mathematical equations and the flowers themselves are guided by the sun. The sunflower has been steeped in mystical magic and worshipped by many cultures, past and present.

But, what is it exactly about the sunflower that makes is stand out from all the rest?

Sunflowers are not just a pretty face, they are members of the Asteraceae family and are grown from seed every year. The stems can be as high as three meters and the largest recorded flower head measured thirty centimeters.

The name ‘sunflower’ also includes all plants of the genus Helianthus, many of which, unlike the sunflower are perennial plants, included in this genus are Jerusalem artichokes.

Unique to the flowering world, the sunflowers ‘flower’ is actually a ‘head’ made up of a mass of tiny flowers all squashed together. The outer petals are called sterile florets and come in a range of colours, bright yellow being the most widely recognized.

The tiny flowers which create a circle are called ‘disc florets’ and are located inside the outer petals, these are what mature into the precious sunflower seeds

A Little History

The sunflower is believed to have been native to the Americas, the first ‘domesticated’ flowers were recorded to have been grown in north Mexican gardens in 2300 BC

European traveller, Francisco Pizarro found his first example of a sunflower in Peru, where the native Incas worshipped their image as a symbol of the sun God. The sunflower was also used as a sun diety by the Aztecs and the Otomi

In the 16th century, the flowers and seeds were brought to Spain, it is said, the Spaniards tried to keep this majestic flower a secret and stop its cultivation, because of its strong links with solar religious beliefs.

Following the Sun

Before bursting into bloom, the unopened flower head, or bud, displays extraordinary behaviour, which is called heliotropism and is the magical part of the sunflower.

Every morning, at sunrise, the unopened sunflowers are turned firmly towards the east, to greet the sun as it rises. During the day, the unopened bloom follows the sun as it travels around to the west to set at the end of the day. During the night, the bud turns once again towards the east ready for the next sunrise.

This unique behaviour is due to motor cells in a flexible part of the stem, just below the bud called the pulvinus as the bud reaches maturity, this flexible part and its motor cells become stiffened and the bud bursts into bloom, with the flower head facing an easterly direction.

A Mathematical Genius

The inner florets of the flower, which will eventually produce the seeds, are arranged in a series of intricate spiraling patterns.

Scientists have found, each little floret leans towards its partner at a precise 137.5° this results in a pattern of interconnecting circles or spirals as they are known. Scientists have also found the arrangement of florets is not a random affair.

The spirals are actually a mathematical equation known as the ‘Fibonacci numbers’ which are a specific series of numbers which are all related to each other by being the sum of the previous two. Starting with 0 and 1, then continuing with: 0,1,1,2,3,5,8,13,21,34 and so on.

On the average sunflower it has been found that there will be 34 spirals in one direction and 55 in the other. The largest sunflowers have 89 in one direction and 144 in another.

So next time you see a sunflower, take time to ‘really’ see it, look at its beautiful face and admire the intricate decoration.

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