Golden Angles.

Back of the Sunflower!  I'm going to make a collograph.  I have had these sunflowers for over two weeks now and they are still standing, but they smell like a going off cauliflower!  I think they will have to go in the compost now.  Shame.  I've really enjoyed them.  

These sunny and joyful plants (as I am always saying) are of course proper plant allies!  They give us those gorgeous seeds, which I love and the birds in my garden love too.  I've just been watching "my" coaltit having a mid morning snack in the garden.  

Interestingly..... and I mean I know this from looking at them ..... the arrangement of the florets is at the golden angle.  Now I'm not an mathematician (grade 3 CSE, good grief) but I love a bit of an equation.  They're pleasing to look at I think!  

${\displaystyle \theta =n\times {137.5}^{\circ },}$

(where θ is the angle, r is the radius or distance from the center, and n is the index number of the floret and c is a constant scaling factor)

This is the Golden Angle.  At this point I'm going to quote Wikipedia because trying to remember this is just beyond my addled capabilities.

"Generally, each floret is oriented toward the next by approximately the golden angle, 137.5°, 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 89 in one direction and 144 in the other. This pattern produces the most efficient packing of seeds mathematically possible within the flower head."

I've taken out the citations, but you can look it up if you need to!  

Also, I have found out that the myth that they turn to face the sun as the day goes on,  isn't exactly true.  Which is good to know, because I have some small lemon coloured sunflowers in my allotment and I noticed that they weren't facing the sun, and I wondered why.  To quote the gardener John Gerard:

 

"[some] have reported it to turn with the Sun, the which I could never observe, although I have endeavored to find out the truth of it."

If you look at a field full of sunflowers, they will be all pointing the same way.  That way is East!  They like to warm up in the morning sun as this attracts more pollinators.  

When the flower is young, it is heliotropic, in that it follows the sun from East to West as the day progresses but a fully mature flower will only face East.  

Another interesting sunflower fact is that they were domesticated in Mexico 2600 BCE.  I am also pleased to report, that like many of the flowers I write about, it is helpful for snakebites!
 
Traditionally, several Native American groups planted sunflowers on the north edges of their gardens as a "fourth sister" to the better-known Three Sisters* combination of maize, beans and squash.  Among the Zuni people, the fresh or dried root is chewed by the medicine man before sucking venom from a snakebite and applying a poultice to the wound.  This compound poultice of the root is applied with much ceremony to rattlesnake bites.

*Anecdotally, people at the allotment this year said that their small beans didn't do so well because it was too hot.  Mine were planted behind the sweetcorn and were great.  The shade helped them survive.