Opuntia "Titania" Spineless Seeds (100 Seeds) Cactus. Opuntia is a large genus of cacti best known as Prickly Pear, Nopal, or Nopales. These cacti are prized for their eatable fruit known as Tunas. The distinctive red-purple juice of the Opuntia fruit can also be used in drinks, candy, jellies, jams, and syrups.