Which plant is the source of the muscle relaxant tubocurarine?

The plant that provides the muscle relaxant tubocurarine is Chondrodendron tomentosum.

This South American tropical liana belongs to the moonseed family, Menispermaceae. Its stems and bark were traditionally used in preparations of curare, an arrow poison used by Indigenous peoples for hunting. The relevant compound is d-tubocurarine, a naturally occurring alkaloid that interferes with nerve signals at the neuromuscular junction.

Tubocurarine does not numb consciousness or act like a modern sedative. Instead, it blocks communication between motor nerves and skeletal muscles, producing progressive paralysis. That property made purified tubocurarine important in the development of surgical muscle relaxation, although safer synthetic neuromuscular blockers have largely replaced it in modern practice.

The wording “source of curare” can create confusion because curare is a broad term for several plant-based poison mixtures, and different preparations may contain different alkaloids. Chondrodendron tomentosum is especially associated with tube curare and d-tubocurarine. Strychnos species were also used in other curare types, but they are not the canonical source of tubocurarine.