Philodendron ilsemanii is a gorgeous, scandent, very rarely offered for sale and seen in collections, variegated Philodendron. The origin of the plant is unkown. It also not known whether it is a species or a hybrid, although it has been suggested that it is a cultivar, as well that it may be a variegated variety of Philodendron corcovadense Kunth (neither of these hypothesis is confirmed).
It should be noted that Philodendron ilsemanii is neither a variegated variety of Philodendron imbe nor Philodendron x domesticum nor Philodendron sagittifolium Liebm. It is also not the same plant as Philodendron 'Jose Buono'.
There is exactly one official record of the plant to be found:  an original plate in Gardeners' Chronicle ser. 3, 43 (1908) from Ghent International Exhibition.
Leaf blades of Philodendron ilsemanii are cordate and slightly elongated, coracieous and thick. The colour is very deep dark green. The variegation is very variable from leaf to leaf and appears as splashes and/ or patches of white with the dark green 'freckles' coming trough.
From the Modern Latin genus name Philodendron (Schott, 1830), from Greek philodendron, neuter of philodendros "loving trees," from philo- "loving" (see philo-) + dendron "tree" (from PIE *der-drew-, from root *deru- "to be firm, solid, steadfast," also forming words for "wood, tree"). The plant so called because it clings to trees.