Botanomancy is a method of divination by means of the burning of leaves, herbs and tree branches. Usually vervain (any of a group of herbs or low woody plants with often showy heads or spikes of five-parted regular flowers) and/or brier (a plant with a thorny or prickly woody stem) were used. Omens were drawn from the smoke and ashes generated. On one of botanomancy's methods the questions for which answers were sought had to be carved upon the branches prior to their burning.

This practice of divination can be traced all the way back to the ancient Druid priests who worshipped the spirits of the trees, specially the oak. There are also a number of botanomancy references in the Old Testament, and the Romans used this mode of divination as well. Botanomancy is a form of Pyromancy.