Spirals, Fibonacci and being a plant

https://www.khanacademy.org/math/math-for-fun-and-glory/vi-hart/spirals-fibonacci/v/doodling-in-math-spirals-fibonacci-and-being-a-plant-part-3-of-3 2 1 4 https://www.khanacademy.org/math/math-for-fun-and-glory/vi-hart/spirals-fibonacci/v/angle-a-trons