The replacement of herbs with synthesized or synthetic drugs is actually new, less then a century old. This is due to drug companies not being able to patent commonly used plants. These pharmaceutical companies employ chemists that can develop synthetic drugs to replace the plant. . . . Which is a billion plus industry.
Here are some of the few of the many plants that are used now . . . .
from Cinchona pubescens also known as the anti-malarial quinine. 10,000 tons of bark is harvested annually to make quinine.
In cancer treatment, the drug Paclitaxel (Taxol) a derivative of the Pacific yew Taxus brevifolia, is used in chemotherapy.
The Madagascar periwinkle Catharanthus roseus, is the source of vinblastine and vincristine, alkaloids used respectively in the treatment of Hodgkin’s disease and pediatric leukemia.
Senna alexandrina, a shrubby perennial native to Arabia, was introduced as a laxative to Europe by Arab physicians in the ninth century. You can find senna in many drugstore laxative products today.
Mentha (mint) species are the natural sources of menthol, an aromatic alcohol which is also known as peppermint camphor. Menthol is an active ingredient in topical preparations to relieve itching and as a mild local anesthetic to soothe soreness and ease muscular tension. Menthol is commonly used in lozenges for sore throats, and is added to inhalers to treat upper respiratory disorders and open congested sinuses.
Peppermint oil, which can still be found in drugstores, is a centuries-old remedy for quelling an upset stomach. Studies show that peppermint oil when taken internally can relieve irritable bowel syndrome.
Gaultheria procumbens, or wintergreen, is a source of methylsalicylate, which is widely used in topical ointments and liniments to relieve muscular pain, and for lumbago, sciatica and rheumatic conditions.
Papaver somniferum, the opium poppy, yields a sap of narcotic opium, from which the potent pain killer morphine is made. Seeds and capsules discovered in the four thousand year old archaeological remains of Swiss lake-dwellers suggest the use of the plant for its narcotic juice. Simultaneously, opium and its products heroin and morphine established themselves among drug users and in the field of medicine. Both uses continue to this day. In modern medicine, morphine and its analogues remain unsurpassed pain killers.
Digitalis purpurea, the purple foxglove, is a popular garden plant cultivated as a source of digitoxin, a cardiac drug which increases the strength of heart beat while decreasing its rate. The plant was recommended for medicinal purposes in the seventeenth century, and has appeared in the French Pharmacopoeia since its first printing in 1818. Digitoxin is used in the treatment of congestive heart failure and other cardiac disorders. Digitalis lanata, the woolly foxglove, is cultivated commercially as a source of digoxin, a cardiotonic used for the same purposes as digitoxin.
Plants and their derivatives are currently the sources for thousands of drugs worldwide. I agree that i doesn't mean that they are all safe or without side effects. Certain parts from the plants like morphine are toxic due to their concentration strength. Small amounts of any can be benefical in a clinical setting. It is good to remember sometimes with medicine . .any you take can be poison with the dose.
Here is some of a list of plants that are used in drugs
Drugs from Plants - Ethnobotany and Chemistry
Again please . . Open your minds.
Remember something you may take every day. . .
Salicin, Willow (salix) bark, which breaks down to become Salicylic Acid or you know as . . . Aspirin