Phyllotaxis for a Sunflower and a Brussels Sprout Stalk

In the sunflower applet, the first seed is placed in the center, and on the brussels sprout stalk, the first sprout is placed at the bottom of the cylinder. Each successive seed or sprout placement is determined by a radial rotation and a movement outward or upward. In particular, each successive seed/sprout is placed around the sunflower or stalk from the previous one, where is the golden ratio. The slider a determines how far out (radially for the sunflower) or up (for the brussels sprout stalk) the next seed will be placed.