"What's at the centre of a sunflower?" asked Harold, squinting as he looked up from his recumbent position on the grass.
"The junction of two spirals, 137.52 degrees apart," said Jasfoup. "I showed that to Leonardo of Pisa, once, and it blew his mind. He wrote a paper on mathematics on it."
"Sort of. On the seeds, anyway. Count the seeds on a sunflower spiral and you'll get two consecutive numbers of the Fibonacci sequence. 21 seeds and 34; 55 and 89 or even 89 and 144 for a really big one."
"You've made me want a pineapple."
See also: Living with twisted willow: Sunflowers - maths, art and the pineapple