In botany, the contrayerva, or contrajerva, is the root and scaly rhizome of various tropical American species of Dorstenia in the family Moraceae (D. contrajerva and D. brasiliensis), a South American plant, the aromatic root of which is sometimes used in medicine as a gentle stimulant and tonic. It was previously used as an antidote to snake bites. The name is used in Jamaica to refer to a species of Birthwort (Aristolochia odoratissima) still believed to have antidotal properties.