6. P. subsect. Philodendron
P. subsect. Philodendron
P. grex Cardiobelium Schott, Syn. Aroid. 88. 1856.
TYPE: P. giganteum Schott
P. grex Eubelium Schott, Syn. Aroid. 92. 1856.
TYPE: P. grandifolium (Jacq.) Schott
P. subsect. Cardiobelium (Schott) Engl. in Martius Fl.
Bras. 3(2): 139. 1878.
P. subsect. Eubelium (Schott) Engl. in Martius, Fl.
Bras. 3(2): 140. 1878.
P. `Gruppe' Cardiobelium (Schott) Engl., Bot. Jahrb.
26: 522, 529. 1899.
As defined by Schott, P. subsect. Cardiobelium consisted of a single species, P. giganteum. The group was greatly expanded by Engler (1899) and by Krause (1913). Now with 20 species, it constitutes the largest subsection in P. sect. Philodendron. The characterization, as expanded by Krause "petioles smooth or lightly striate, asperate; blade cordate to sagittate, with the primary lateral veins much more conspicuous than the secondary veins", is defined so broadly that many unrelated species might easily be contained within it. Certainly to be excluded is P. rubens Schott (now a synonym of P. ornatum and the core species in P. sect. Psoropodium). Among the well known and seemingly distinct taxa included by Krause are P. grandifolium, P. acutatum Schott, and P. fraternum, all with deciduous cataphylls and P. tenue, P. schottianum, and P. panamense with persistent cataphylls. The type species P. giganteum is also a species with conspicuous persistent cataphylls. A particularly unusual species included by Krause is P. quitense Engl., a species with deeply three-lobed leaves. It would not appear to be closely related to others in the group.
The only Central American species included in the section by Krause were: P. brevispathum, P. panamense, P. schottianum, and P. tenue. Philodendron brevispathum with its scaly stems is best accommodated with P. muricatum in P. subsect. Solenosterigma.
Philodendron subsect. Philodendron has 20 species in Central America. The size and diversity of P. subsect. Philodendron warrant the creation of subsections which are presented below: