2 series of spirales
"Sunflowers seem to have a preference for arrangements with two series of spirals. A first serie consists of a Fibonacci-number spirals and a second serie, in opposite direction, in which the number is the next Fibonacci number. Although there are exceptions, the general rule is quite remarkable."
(Chris Impens, pointing to a study by Jonathan Swinton.)
The pictures below (with reference number) come from a database with this study.
21/34 sunflower with 21 red spirals (clockwise) and 34 blauwe (counterclockwise)
34/55 sunflower with 34 blue spirals (clockwise) and 55 red (counterclockwise)
55/89 sunflower with 55 red spirals (clockwise) and 89 blue (counterclockwise)
