Anagallis phenicea.

Botanical name: 

ANAGALLIS PHENICEA. Lam. Red Pimpernel. From New York to Carolina. Seemingly inert, yet acrid and active. Believed useful in hydrophobia by Boerhaave, and ever since. Employed in Europe for mania, epilepsy, melancholy, &c. thus useful in all nervous diseases; Clayton recommends it in febrile delirium. Also pulmonic and alexiter. It is poisonous to cattle; yet Colden says the decoction was used in New York in the bloody sweat or murrain of calves.

Medical Flora, or Manual of the Medical Botany of the United States of North America, Vol. 2, 1830, was written by C. S. Rafinesque.