Whilst reading about old rituals you cannot help but notice the use of plants in them. One such plant Vervain (Enchanter's plant, Herb of the Cross, Holy herb, Juno's tears, Pigeon's grass, Pigeonweed, Simpler's joy, Herb of Grace) or given it's latin name Verbena officinalis was used by Levi whilst doing his famous summoning and has connections with Midsummers Eve. It was a sacred herb of the Druids and was called hiera botane, or sacred plant, by the Romans. It is a known sedative, relaxant, nerve tonic, thymoleptic, spasmolytic, mild diaphoretic, hepatic, reputed galactagogue.
Obviously the pharmacology properties of plants is extremely important and even more so in pre-industrial times. I should imagine that with vervain being a relaxant amongst other things it's properties would have been noted as being useful for rituals. Does anyone know of anymore such plants with links to mystical rites?