Harrisia is the name of a cactus plant native to South America. It is also known as "Queen of the Night" because of its stunningly beautiful flowers that bloom only at night. However, there are many other synonyms for the word "harrisia" that are used in different parts of the world. For instance, in Brazil, it is called "flor de maio" or Mayflower, while in Argentina, it is known as "reina de la noche" or Night Queen. In Mexico, it is called "flor del vampiro" or Vampire Flower due to its nocturnal blooming. Other names for harrisia include Moon Cactus, Night-Blooming Cereus, and Lady of the Night, to name a few.