The breeding system of an Ohio population of Synandra hispidula was investigated. Flowering individuals were subjected to four pollination regimes: 1) isolation inside insect exclosures without further manipulation; 2) self-pollination by hand in a pollinator-free environment; 3) excision of anthers in a pollinator-free environment; 4) open-pollination (control). Regimes 2 and 4 yielded over 80% seed set and did not differ significantly, regime 1 yielded 46% seed set, and regime 3 resulted in no seed production. Synandra is self-compatible and capable of spontaneous autogamy. The rarity of this monotypic genus is not likely the result of poor pollination.