well it depends on the plant but for the most part you'd probably be taking either extracts or pills, or maybe making a tea yourself or something. just look up aprhrodisiacs.. or... here's a site where you can order all kinds of legal drugs i mean herbal ethneobotanicals FOR MEDICINE
http://www.bouncingbearbotanicals.com/
I can't really remember the names of the herbal aphrodisiacs so you might have to look them up ;o if you click the herbs under the herbal page it gives you a description of what it is used for.
Notice they sell toad there ;o lol
also ayahausca, amanita muscaria (legal berserker shrooms) and san pedro a legal peyote replacement.