I found several references tonight on UBC stating the name Philodendron cordatum was a synonym (or vice versa) for Philodendron scandens oxycardium which is correctly Philodendron hederaceum. Scientifically Philodendron cordatum is endemic only to Brazil and is not closely related to Philodendron hederaceum or any of its many synonyms. If you check any of the major scientific data bases (TROPICOS or IPNI) you won't find either plant listed as a synonym for the other. I'm not certain how this claim became popular but suspect it originated in one of the popular horticultural texts. That notion is nothing more than a horticultural myth. The plants don't look alike and grow in very different ways. I've corresponded a great deal with aroid botanist Dr. Marcus Nadruz who is the director of the Rio de Janeiro Botanical Garden in Brazil and he has confirmed that claim is absolutely incorrect. The only synonym for Philodendron cordatum Kunth is Arum cordatum which is simply a very old name used when the plant was considered to be in the genus Arum. The common name for Philodendron cordatum is Philodendron Angra dos Reis and the species is primarily a coastal species found growing on rocky shorelines near Rio. The name Angra dos Reis means "King’s Cove" in Portuguese and is a city approximately 150 km (60 miles) southwest of the city of Rio de Janeiro, Brazil. Famous for its coastline on the Bay of Ilha Grande with its 365 islands, the name Philodendron Angra dos Reis appears to have been used in a seed list from the late 60's and early 70's according to Harry Luther at Marie Selby Gardens in Florida. The blades can grow large and both the petioles and the midrib often possess purpish spots. Rather than go into a great deal to try to explain the science of this species you can read it here should you desire: http://www.exoticrainforest.com/Philodendron cordatum pc.html The attached photo was provided by the Marie Selby Botanical Gardens in Sarasota, FL and is used with permission.