P. subsect. Macrolonchium (Schott)
Martius Fl. Bras. 3(2): 139. 1878.
Though neither short stems nor D-shaped petioles are unique to this group, it appears to be a natural one at the subsectional level with the exception of only two pinnately lobed species in the group, P. pinnatifidum (Jacq.) Schott and P. robustum Schott. Those species are very similar to P. fendleri K. Krause, which Engler placed in his P. sect. Polytomium. Philodendron pinnatifidum and P. robustum should probably be placed there as well. They seem to have little in common with the other simple leaved species. Philodendron melinonii Brongn., P. fragrantissimum, P. simsii Kunth, and P. roraimae K. Krause all appear to be related. The only Central American species in this subsection is P. fragrantissimum.