平原菟丝子（学名：Cuscuta campestris）为旋花科菟丝子属下的一个种。

Cuscuta campestris, with the common name large-seeded alfalfa dodder and prairie dodder, is a parasitic plant which belongs to the family Convolvulaceae. It was formerly classified in the family Cuscutaceae.

It is native to central North America. It is a parasite of a wide range of herbaceous plants.