Lu Yu, one of the original tea connoisseurs and author of The Classic of Tea, a treatise on tea in the eighth century, advised against mixing teas with other ingredients. "One must guard against...adulterating it with other plants or herbs," he wrote.
The tea plant, Camellia sinensis, provides a bounty of different teas, ranging in the thousands, and each unique in flavor because of the terroir, varietal, harvesting methods, and processing that influence it. Truly good teas need no flowers, fruits, sweeteners or other flavorings to enhance them, and in fact, may even have a negative impact on them.
Many tea merchants will offer at least a small selection of "adulterated" teas for the tea person who craves jasmine or chrysanthemum in their tea, but the connoisseur will generally seek out the essence of a tea in its pure form. Snobbery aside, the tea aficionado will tend to be more interested in single estate, single lot, even single trunk teas (which come from only one tea bush or tree), and rarely, if ever, teas mixed with fruits, flowers, herbs or spices.
There is something really special about knowing the flavor and other characteristics of one plant on its own. If you want to know rose, drink rose; if lavendar, drink lavender; but if you want to know tea, drink just tea!
I love a great chai and also love flower/herb tisanes. But to really undersand and appreciate tea at its finest, you will want to seek out unflavored, unblended teas that are processed at a level that produces an incomparable taste and experience that cannot be duplicated or "improved" with the inclusion of other plants and spices.