I agree
@purpleinopp that the IAS is the definitive source for aroid ID. But like you said, things can be slow to update. Their membership is not what it used to be and the actual scientific authorities like Peter Boyce and Dr. Thomas Croat and Julian Boos do not seem to be as active as in the past. I am a member of the IAS and remember when it was extremely active...there is almost no activity on forums and mailing lists now. They still do publish a great quarterly journal, the last one from March was all about Dr. Croat's trip to Ecuagenera (who I have bought many plants from in the past) and documenting his collection of several new species of Anthurium and Philodendron.
I think that the false terminology in the present plant trade for Pothos, Scindapsus, and Epipremnum is so totally entrenched in the market that it will never be able to be changed. The only people who are willing to do their own research and discover what they are actually being sold (or RESOLD under another name) are people who are serious about collecting, on either a large or small scale.
Pothos is its own genus. It contains about 55 plants, almost none of which are currently readily available to the US plant trade. The plant known as pothos (devil's ivy) that is commonly sold (in all its cultivars...NJoy, Jade and Pearls, Neon, etc) was once considered a member of this genus but has not been included in the Pothos genus for some time. It was moved to the genus
EPIPREMNUM which has about 15 species, the most common being sold in the plant trade are pinnatum, aureum and giganteum (giganteum is difficult to locate and a collectors item, a friend of mine just obtained one last weekend from a fellow IAS member in South Florida, he had been looking for one for years)
Scindapsus is also a separate genus containing about 35 species. The most common are pictus in the small leaved form and the 2 larger leaved forms, and treubii, which is very rarely found in nurseries but sometimes you get lucky.
NONE of these plants are PHILODENDRONS although they are commonly referred to in the plant trade that way, mainly because the people selling them do not seem to care or know any better what they call their plants as long as they sell mass numbers of them to the plant buying public.
I don't mean to sound harsh, this is just the way I view this subject. I only have a limited amount of money to spend on plants, and a limited amount of space and resources to use on them. When I do let go of a dollar, I want it to be for the genuine article of something, not a misnamed plant that has been mislabeled and is not what it is supposed to be. That is why I am a plant geek and do a lot of research.
This site uses the Catalog of Life or whatever it is called for the definitive source of its taxonomy...and because this source is slow to update, they do not accept the fact that several common Philodendrons (including Xanadu and selloum) have been removed from the genus Philodendron and placed into an entirely new genus, Thaumatophyllum, which is now beginning to be used by serious collectors who trade and sell plants from their collections. The retail plant trade will probably never catch up to that change.
