Ginseng

Can you explain the different types of Ginseng and how they'd be used. I am currently needing Siberian Ginseng for an ADHD extract. While researching it, I come to realize there are a few other types/differences. I am now wondering if I should also include the Panax type into my supply. I have read that the Siberian is completely different than the others (American, Panax, etc). Which do you find being used the most in various extracts/tinctures, etc.? I don't want to end up an abundance of just one kind that I'll rarely use or only have on hand for a specific blend. Just building my supply slowly but surely. Any help is appreciated.