Dave: Yes, I noticed that it said it was a naturally occurring form of P. domesticum and yes, mine looks identical to the plants pictured in the first link you provided; maybe it was the sp. cordatum that was confusing me.
Evan: the photo in the database (even the light colored leaves) look more rounded and heart shaped than the leaves on my plant which are larger and elongated in shape. When I zoom way in on the plant in the database I don't see the pinkish red petioles on any of those leaves as described for P. 'Lemon Lime'. It does make sense though that the plant pictured in the database would be called Lemon Lime because of the two shades of leaves being the colors of lemons and limes.
Swayback: I have, or had Philodendron 'Moonlight' (I need to go in search and see if it's still around), it's definitely a self heading type of Philo. If Brian said your plant that resembles mine is a hybrid of Moonlight, I'd trust his expertise. I will be interested to see your photo's for comparison to my plant.
I sure appreciate everyone's input here! Thanks so much!
