PENNYROYAL  , in

botany, a herb formerly much used in medicine, the name being a corruption of the old herbalist's name " Pulioll-royall," Pulegium regium . It is a member of the mint genus, and has been known to botanists since the time of Linnaeus as Mentha pulegium . It is a perennial herb with a slender branched stem, square in section, up to a foot in length and rooting at the lower nodes, small opposite stalked oval leaves about half-inch long, and dense clusters of small reddish-purple flowers in the leaf axils, forming almost globular whorls . It grows in damp gravelly places, especially near pools, on heaths and commons . It has a strong smell somewhat like that of spearmint, due to a volatile oil which is readily obtained by distillation with water, and is known in pharmacy as Oleum pulegii . The specific name recalls its supposed property of driving away fleas (pulices) . Like the other mints it has carminative and stimulant properties .