Homeopathy is a system of medicine that uses naturally occurring substances in remedy format to stimulate the body’s natural ability to heal (consider how skin grows back after a wound).
To become a homeopathic preparation substances go through serial dilution and succussion or shaking which means they interact in a very gentle way with the body.
Remedy substances are not confined to the plant kingdom but come from mineral and animal kingdoms as well so for example you have remedies made from nettles, granite and substances such as a bee sting or snake venom.