To give you an idea of how I created & integrated this visual library, I first did a lot of research, (mostly online but also in a few books) to try to gather all the different possibilities of leaf structure/shape/edges and venation. I then organized them in a way that made sense to me, and hopefully to you. :) I drew the finished library, as you saw in the videos, and REPEATED drawing these (this is the part I didn't show you), while partially hiding/referring back to the main library if I felt like I forgot one. Once I felt like the library was very integrated, I did the first initial sketch which you saw in the demo. In this drawing, I was really concentrating on creating plants where each one was different from the last, in terms of size, type, edges, structure, edges, veins, and even the way the leaves were arranged within the plant (are they thick and close together, creating a bush-like effect? Or are they far away from each other? Do the leaves oppose each other? Or are they arranged in a circle around the stem? Are the leaves bigger than stems or are the stems bigger than the leaves? Or are there no stems? What type of veins do the leaves have?). This was more of an exercise to try to really consolidate what I remembered from the library.

After that, I felt like I was quite comfortable and integrated all the different possibilities of the visual library. I then went on to create 5 or 6 drawings with different plants, this time having fun exploring different ways of putting them together. Sometimes I created single plants, sometimes a multitude of plants, but always keeping in mind the 'personality' of each one, and how changing the size/shape/edges/veins and overall structure made a visual difference.

I also used some beautiful little frames I'd collected to put the 'finishing touch' to these drawings. :)

This was the first: 

 

and here are a few more: 

 

 

I decided to stay in black and white (because I thought it looked cool with the frames :) ) but you're welcome to use color and add other textures. As I said in the video, experiment! You can even decide to do a completely abstract drawing with just a few little leaves mixed in, or try out other types of shapes/sizes/structures/veins/edges, just for the fun of it and see where it brings you. 

I can't wait to see what you make so please share your project in the project section so we can see what you made and I can talk about it with you! 
Good luck and have fun :)