P. sect. Macrogynium Engl., Bot. Jahrb. 26: 553. 1899.
TYPE: P. hoffmannii Schott
Philodendron sect. Macrogynium is one of two small sections treated by Krause (1913) (the other being P. sect. Camptogynium). Philodendron sect. Macrogynium consists of a single species, P. jacquinii (treated by Krause as P. hoffmannii). Both sections are represented by scandent species, distinguished by having the style prolonged and much narrower than the ovary and a single ovule per locule. Despite these similarities the two sections are very different from one another. Philodendron jacquinii (P. sect. Macrogynium) has setose stems, thin, veiny, ovate-cordate blades which may be deciduous during the dry season. Its spathe is bulbous and roomy inside, quite unlike most members of species in other sections. The style, though narrowed to the apex, has a typical, hemispheroid stigma. For differences with P. sect. Camptogynium see below.
Philodendron brevispathum, with its similarly to P. jacquinii might be considered a relative, but the former has branched scales, not simple trichomes on stems and petioles, has a normal, sessile style and has 6-14 ovules per locule with axile placentation, rather than 2 ovules per locule and sub-basal placentation for P. jacquinii.
This section appears, at least on the surface, a natural one. There is no other species known which is like either morphologically or ecologically. Its thin, veiny leaves are deciduous in the dry season and the large colorful infructescences are prominently displayed in a mostly deciduous environment.