Here is a shockwave flash tutorial on how i model flowers without textures… you can apply the same concept for making plants, just use a leaf or a branch rather than a flower pettal:
If you want a scaleable version Here is a hotlink : (can use a minimal sized window, but may distort image)
Here is Yet another snapshot, and I included a blend files as well.
you are welcome to use this any way you see fit… have fun!
Here is the blend file: