Loving all the wonderful Aroid photo's! I wish I had shade and space for a jungle, heck I'd just love to have one giant live oak on my property!
Elaine: I copied this from Wikipedia, could it be what your P. sagittifolium is exuding?
Extrafloral nectaries: Some philodendrons have extrafloral nectaries (nectar-producing glands found outside of the flowers). The nectar attracts ants, with which the plant enjoys a protective symbiotic relationship.[15] Nectaries can be found in a variety of locations on the plant, including the stalks, sheaths, lower surfaces of the leaves, and spathes. The nectaries produce a sweet, sticky substance the ants like to eat and which provides an incentive for them to build their nests amongst the roots of the given philodendron. In some cases, the amount of nectar produced can be quite extensive, resulting in the surface becoming entirely covered with it.