Do you have a Citrus Astera? If yes, you could cross your Fourpetal Reptans with that to get a Venomous Grass, and then cross the Fourpetal Reptans again with the Venomous Grass. The same principle works for Citrus Maranta, Citrus, Maple or Citrus Ball Cactus.

hmmm, I just figured out that with a Fourpetal Reptans you can get to the Aureus Scandens starting with any Citrus, Mela, or Venomous plant. It just may take many generations!