This section of the book is from "The Complete Herbalist" by Dr. O. Phelps Brown. Also available from Amazon: The Complete Herbalist: The People Their Own Physicians By The Use Of Nature's Remedies.
I repeat, from what has been seen it is evident that all herbs perhaps possess some property suitable for medical purposes. These virtues may be found in the root of one plant, in the bark of another, in the leaves of another, in the blossoms of another, in the seeds of another, or in the whole combined. Even the color of the flower has much to do with the therapeutic properties of the plant -- as, for instance, the Blue Vervain, as used in my Fits and Dyspepsia remedy, is the only kind that is used for medical purposes -- all the other species being entirely useless, or else more or less dangerous.
In fact, it is evident to the comprehension of the simplest mind that climatic influences have much to do with the full development of plants. This may be illustrated in the Tobacco raised in Cuba and that grown in Connecticut -- the one being grown in a Southern and the other in a Northern climate. The poison nicotine is derived from the tobacco plant; the exhilarating caffeine and theine are obtained from the coffee berry and tea plant. Thus it is possible that some therapeutic agent or other may be derived from every plant grown on the surface of the globe.
The Red Men of the American forests are never at a loss to know which plant is best, nor the time it should be gathered, to cure them of disease. They know how to treat their complaints in physic, surgery, and midwifery with a skill that far surpasses that of many a learned doctor of the big medical schools, with all their science, and the medical teachings of physicians for upwards of four thousand years. What other guide have the poor Indians -- those untutured savages of the woods--but their reason and their instinct, and their practical experience in the use of herbs?
This is the same in the East Indies, South America, South Sea Islands, Patagonia, Africa, and other lands The negroes in the interior parts of Africa possess a knowledge of the medicinal properties of plants which is really surprising, and, by consequence, are rarely afflicted with disease. The art of healing in Sumatra consists in the application of plants, in whose medicinal virtues they are surprisingly skilled. In fact, the Sumatrans have a degree of botanical knowledge that surprises the European or American. They become acquainted at an early age not only with the names, but the qualities and properties of every shrub and herb among that exuberant variety with which their country abounds.
In gathering herbs for medical purposes, we should not only know the season when they should be culled, but we should be qualified to comprehend the principles of which the plant is composed -- whether they be resins, alkaloids, or neutrals -- and be able also to separate the one ingredient or element from the other, as a distinct medicinal property, or combine the whole for the purpose of a compound medical agent.
Plants by their appearance often invite the invalid to cull them for his restoration, and assume such shapes as to suggest their curative properties. For instance, herbs that simulate the shape of the Lungs, as Lungwort, Sage, Hounds-tongue, and Comfrey, are all good for pulmonary complaints.
Plants which bear in leaves and roots a heart-like form, as Citron Apple, Fuller's Thistle, Spikenard, Balm, Mint, White-beet, Parsley, and Motherwort, will yield medicinal properties congenial to that organ. Vegetable productions like in figure to the ears, as the leaves of the Coltfoot or Wild Spikenard, rightly prepared as a conserve and eaten, improve the hearing and memory; while oil extracted from the shells of sea-snails, which have the turnings and curvings of the ears, tends wonderfully to the cure of deafness. A decoction of Maiden Hair and the moss of Quinces, which plants resemble the hairs of the head, is good for baldness. Plants resembling the human nose, as the leaves of the Wild Water Mint, are beneficial in restoring the sense of smell. Plants having a semblance of the Womb, as Birthwort, Heart Wort, Ladies' Seal or Briony, conduce much to a safe accouchement. Shrubs and Herbs resembling the bladder and gall, as Nightshade and Alkekengi, will relieve the gravel and stone. Liver-shaped plants, as Liverwort, Trinity, Agaric, Fumitory, Figs, etc., all are efficacious in bilious diseases. Walnuts, Indian nuts, Leeks, and the root of Ragwort, because of their form, when duly prepared will further generation and prevent sterility. Herbs and seeds in shape like the teeth, as Toothwort, Pine-kernel, etc., preserve the dental organization. Plants of knobbed form, like knuckles or joints, as Galingale, and the knotty odoriferous rush, Calamus, are good for diseases of the spine and reins, foot, gout, knee swellings, and all joint pains whatsoever. Oily vegetable products, as the Filbert, Walnut, Almond, etc., tend to fatness of the body.
Plants naturally lean, as Sarsaparilla or long-leaved Rose Solie emaciate those who use them.
Fleshy plants, such as Onions, Leeks, and Colwort, make flesh for the eaters. Certain plants, as the Sensitive plant, Nettles, the roots of Mallows, and the herb Neurus, when used as outward applications, fortify and brace the nerves. Milky herbs, as Lettuce and the fruit of the Almond and Fig trees, propagate milk. Plants of a serous nature, as Spurge and Scammony, purge the noxious humors between the flesh and the skin. Herbs whose acidity turns milk to curd, such as Galium and the seeds of Spurge, will lead to procreation. Rue mixed with Cummin will relieve a sort breat, if a poultice of them be applied, when the milk is knotted therein; while plants that are hollow, as the stalks of Grain, Reeds, Leeks, and Garlic, are good to purge, open, and sooth the hollow parts of the body. Many more instances of such adaptation of herbs and plants to diseases of the body might be cited if deemed necessary.
The vitality of plants may be destroyed by giving them deleterious or poisonous substances, such as arsenic, mercury, etc. In fact, mineral poisons act on plants and herbs in nearly the same way they do upon human beings or other animals.
The color of plants is generally under the influence of solar light; hence, plants grown in darkness become etiolated or blanched. The green of leaves is due to nitrogen, while in proportion as the oxygen of the air predominates, the leaves put on varied tints, as the beautiful red and crimson assumed by some leaves in Autumn.
The color of flowers, as a general rule, is influenced by solar light, though the magnetic condition of the soil has much to do with the color. For instance, the petals of the common butter-cup are of as brilliant a yellow in town gardens enveloped in the smoke of London as on any country hill, while the tints of the rose remain, when languishing for lack of a clear atmosphere. The flowers of the common hydrangea, which are naturally pink, may be made blue by planting the shrub in soil impregnated with iron. So will certain medical preparations of iron turn blue the human flesh. The color of the flower of the tulips can be turned into white, yellow, brown, purple, and a beautiful tint of rose, by transplanting the plants from a poor soil to a rich one, and vice versa.
The fragrances of flowers and plants have their physiological or medical uses. The use of the fragrance in leaves, bark, and wood, is apparently to preserve them from the attacks of insects; as the smell of the red and Bermuda cedars (of which pencils are made) and of Camphor, also a vegetable product, is to keep moths and other vermin from attacking substances with which they are in contact.