Vervain used in a sentence

Vervain in a sentence as a noun

If I knew Only the herbs and simples of the wood, Rue, cinquefoil, gill, vervain and agrimony, Blue-vetch and trillium, hawkweed, sassafras, Milkweeds and murky brakes, quaint pipes and sun-dew, And rare and virtuous roots, which in these woods Draw untold juices from the common earth, Untold, unknown, and I could surely spell Their fragrance, and their chemistry apply By sweet affinities to human flesh, Driving the foe and stablishing the friend,-- O, that were much, and I could be a part Of the round day, related to the sun And planted world, and full executor Of their imperfect functions.