Old fashioned, here is a definition (paraphrased) from one book I use,
Herbal Healing for Women, by Rosemary Gladstar.
Infusions and Tisanes -- Brewing herb teas. Infusions (also called tisanes) extract the easily rendered vitamins, mucilage and delicate volatile oils. Used when preparing the more fragile parts of the plant: leaves, fruits, seeds, flowers and roots with a high concentration of volatile oils. There are 4 methods commonly used to make an infusion (and this gets into much detail, but is basically what you do when you brew tea--pour boiling water over them and let them sit for anywhere from 3 or 4 minutes, to 20 minutes, or even overnight--depends on the herb you are using).
Decoctions -- Are used to extract more tenacious plant material and are generally used for brewing roots, barks, nuts, and non-aromatic seeds. There are exceptions though, some roots contain volatile oils that would be easily destroyed by high temps (such as goldenseal or valerian) and those would be better to do an infusion. There are 3 common methods used to decoct herbs (more extensive detail). In general this involves placing the herbs into a pot of cold water, covering with a tight fitting lid and slowly bringing it to a boil, reducing to a simmer for about 15 to 20 minutes. Then you either strain and drink hot or you can leave it in the pan with the lid on overnight for an even stronger tea.
There is a lot of good detail in that book on different methods of preparation. Other than teas, there are some things you would tincture in alcohol (ie. gin), or oil (like olive oil or sweet oil), some things you grind and use as a powder or capsule, and some things can be added to a cream as well.
I always thought it would be great to get to the point of being knowledgable enough to stock my own medicine cabinet with some things. I am definitely going to tincture my valerian next year! Today has been one of those days where I wish I had some right now!
Hehe...
Thanks
