In the process of becoming familiar with herbalism, it’s easy to feel confused by jargon that, while clearly obvious to those using it, tends towards being something of an insider’s tongue. This can cause beginners to feel alienated from group discussion that could be educational and intimidated by what should be common sense concepts. Because of that, I’ve decided to start a series of posts called “Terms of the Trade” that will provide a simple definition of the term(s), and a sample context in which it might be used. I don’t plan to make this complex or exhaustive, but for it to serve as a clear introduction to those unfamiliar with, or confused by, herbal terminology as well as a refresher course for more experienced practitioners looking to refine their understanding.
The term diffusive has been coming up more and more in recent herbal conversations. Although a generally archaic term, it has become somewhat common with the revival of physio-medical thought in modern herbalists. What most people don’t know is that diffusive is only one part of a symbiotic set. The other, the word permanent, I don’t hear nearly as much but is an important element in understanding the former term.
To diffuse is to spread something widely. In herbalism, it generally refers to any agent that has a powerful, rapid, and sometimes transient effect on the body through the nervous system. This impression can often first be felt upon the tongue as a tingly sensation, as with Echinacea, Wild Ginger, Bayberry or Prickly Ash.
Permanent refers to those plants which act on the body in a slower, less jolting and more persistent manner. This especially applies to many nourishing herbs such as Milky Oats but can also be felt in many, many other plants.
It is important to realize that a plant can have both a diffusive and permanent action on the body, in varying proportions and degrees. Cayenne is a common example of this, being first felt through its rapid effect on the nervous system which fades, but then persists in a more permanent, slow way on the whole body. William Cook puts it this way:
“These terms are, of course, merely relative; for some agents which are absorbed (as capsicum) may first make a diffusive impression through the nerves, and follow this by an influence of a slower and more persistent kind through the entire frame. But, while this nomenclature is not absolute, it is sufficiently explicit to warrant its general use — employing the terms only as referring to time, and not to extent.”
So how is this useful to the novice or practicing herbalist? Well, understanding both the differences and overlaps of these terms will allow us to better understand the action of the plant in the human body, and to thus better see what is required. In some cases, diffusives can help to potentiate the effects of more permanent herbs, to speed and strengthen their effects. For instance, TJ Lyle states in Physio-Medical Therapeutics that:
“Hepatics, cathartics, stimulants and nervines will usually be more effective if combined with some diffusive, and a less dose will be required.”
Basically a diffusive can help nudge the other plants into acting quicker, stronger and in a smaller dose. They work through the sensitive nervous system to effect the whole body. On the other hand, very diffusive herbs can be rendered safer, more nourishing and longer lasting through being combined with a permanent plant. Because of this, diffusive herbs are often added in small amounts to nearly every formula and are sometimes considered harmonizers as well as potentizers. Ginger is a perfect example of this, serving to spread the effect of the overall medicine more promptly through the body, and increase the immediate as well as long term effects. This is why I often combine Peach and Ginger, especially for use in digestive or nervine matters, for Ginger speeds the spread of the calming influence while the Peach soaks in and saturates the whole overactive system with its sweet yet firm touch. In the same way, the lymphatic effects of Burdock will be felt more quickly if a small percentage of say, Echinacea or Ginger, is added to it. This is why we can still see small sprinkles of Cayenne added to many older formulas, not so much because the practitioners were obsessed with hot peppers, but because it was an easily available and highly effective way of increasing the potency of the medicine.
Physio-Medical Therapeutics by TJ Lyle
Treatise on Therapeutics by William Cook
The Admirable Secrets of Herbs, Roots & Barks by Matthew Wood