A genus of tropical trees and shrubs belonging to the Logania family (Loganiaceae). Strychnos nux-vomica, a native of India and Ceylon, is the source of strychnine (see illus.). The alkaloid, strychnine, has been used medicinally in the treatment of certain nervous disorders and paralysis. Curare, used by the Indians to poison arrows, is obtained from S. toxifera and S. castelnaei in Guiana and Amazonas and from S. tieute in the Sunda Islands. Curare paralyzes the motor nerve endings in striated muscles and is used in medical practice in cases in which a state of extreme muscular relaxation or even immobility is desirable. It has become an important drug in the field of anesthesiology.