Plants arrange leaves, seeds, and petals using the golden angle α = 2π(1 − 1/φ) ≈ 137.508°, where φ = (1+√5)/2 is the golden ratio. This produces Fibonacci spiral arms — the number of clockwise and counterclockwise spirals are always consecutive Fibonacci numbers. The golden angle is the most "irrational" number, maximizing packing efficiency and light exposure.