Northern Jack in the Pulpit (Arisaema stewardsonii) bearing fruit; photographed in Conway, New Hampshire. Arisaema species occur throughout eastern North America. They contain oxalic acid, so are poisonous if ingested; although if properly dried or cooked they can be eaten as a root vegetable. Native Americans used a preparation of the root for a number of medicinal purposes: primarily to treat sore eyes, but also to treat rheumatism, bronchitis, and snakebites, as well as to induce sterility.