Which is cultivated across more continents, Clintonia or Washingtonia? 
Clintonia:  It is distributed across North America and eastern Asia where it is found as an understory plant in woodlands. Washingtonia:  Both "Washingtonia" species are commonly cultivated across the Southern United States, the Middle East, southern Europe, and north Africa, where they have greatly hybridized.
Washingtonia