Unlike other types of tea, herbal teas don't contain caffeine. White, green or black teas, however, contain between 14 and 61 milligrams per 6- to 8-ounce serving, with longer steeping times leading to higher amounts of caffeine. Even decaffeinated versions of these teas contain about 12 milligrams per serving. There's a simple explanation for this -- herbal teas are made using different plants than true teas.
Herbal teas are made from various combinations of herbs, dried fruits and flowers, while true teas, including Pu-Erh, oolong, white, green and black teas, are made from tea leaves from the Camellia sinensis plant. Herbal teas don't contain any actual tea leaves. Yerba mate, or mate, a beverage made from the leaves of a South American holly tree, is one exception, as it does contain caffeine.