What is the appropriate usage of the length factor in an L-System?

Question

I'm just starting out with procedural generation and I've made a program that generates lines using a D0L-systems by following Paul Bourke's website. For the first two simple examples it works great, but when I input the rules of the L-System Leaf, my results are incorrect as can be seen on this image.

Could any of you more experienced people point out where I might be going wrong? I'm pretty sure that I'm misunderstanding something about the usage of the length factor. In my case, lengthFactor is a static float, that is set once before the generation starts and is used to multiply/divide line's length in the current drawing state. lenghFactor itself won't change during the generation.

I'm using OpenGL for rendering and programming in C++.