A tea, to the lay person, conjures up images of prepackaged, individually wrapped tea bags. And while the herb itself may have medicinal properties, the tiny amount in each bag is not likely to have any medicinal effect. One notable exception is a commercial tea bag which contains Ephedra , the plant genus from which ephedrine is isolated and extracted. Two lawsuits against the tea company were filed when hypertensive patients suffered strokes after drinking the tea. An infusion is used when it is necessary to preserve the volatile, or essential, oils of a plant.
Volatile oils evaporate quickly in the presence of heat and air.
The container is then covered and the infusion allowed to steep from 10 to 30 minutes, depending on the strength or density of the herb. Other factors, such as the particular volatility of the oil, may also come into play. Because the hard parts are denser than leaves and flowers, a higher temperature is necessary in order to extract the active properties. So decoctions are simmered or boiled. A mixture of two cups dried herb to two cups water is simmered 1- to 30 minutes, or until half the liquid volume has evaporated.