Aristolochia clematitis, the (European) birthwort, is a twining herbaceous plant in the family Aristolochiaceae, which is native to Europe.

The leaves are heart shaped and the flowers are pale yellow and tubular in form.

It was formerly used as a medicinal plant, though it is poisonous, and is now occasionally found established outside of its native range as a relic of cultivation.

It is now thought to be the cause of thousands of kidney failures in Romania, Bulgaria, Serbia, Bosnia and Herzegovina and Croatia.

The initial hypothesis that seeds from the plant were unintentionally consumed through contaminated flour has come to be questioned.