Short · Nature
Why do sunflower seeds form spirals?
Turn every new seed by the same angle. A third of a turn leaves three straight arms with gaps; the golden angle, about 137.5°, packs the head evenly into 34 and 55 spirals.
Try it yourself
Opens Sunflower Lab. Change the same thing yourself.
Transcript
Why do sunflower seeds form spirals? Going out from the center, each seed is turned by the same angle from the one before. Turn a third of a circle each time, and the seeds stack into three straight arms, with wasted gaps between. Now nudge the angle to about one hundred thirty-seven and a half degrees: the golden angle. No two seeds ever line up exactly, so they fill the head evenly, and spirals appear, often thirty-four one way and fifty-five the other. Try it yourself at Explainer Tools dot com.