Philodendron subsect. Glossophyllum consists of two series, Glossophyllum and Ovata, the latter new.

Philodendron ser. Glossophyllum as defined here, has the appearance of being a very natural group of species with more or less oblong leaves which are acute or frequently cordulate or subcordate at base. The primary lateral veins are usually distinct. Stems are typically somewhat scandent though some members of the group, such as

P. auriculatum, P. bakeri, P. dolichophyllum, P. ligulatum, P. morii, P. pseudoauriculatum, P. utleyanum, and P. wendlandii, sometimes have internodes scarcely longer than broad. Petioles are usually spongy or subspongy, usually subterete and often bearing a purplish or greenish annulus around the circumference where the petiole joins the blade; cataphylls may be unribbed or sharply 1-2-ribbed and are typically deciduous (though persisting for a time in some species with short internodes, e.g., P. auriculatum and P. wendlandii. Style type is variable in the group with most having B or D type styles but with one species, P. granulare having an unusual type E style. Philodendron ser. Glossophyllum ranges from Nicaragua to Colombia and Ecuador on the Pacific slope and to the Guianas and the Amazon basin.

Although Krause characterized P. subsect. Belocardium as having uniovulate locules and spongy petioles he placed a number of species in P. sect. Glossophyllum which have decidedly different blades, being either conspicuously cordate or sagittate. Among these were: P. subovatum Schott, P. densivenium Engl., P. lindenii Schott, P. weberbaueri Engl., P. smithii, P. subhastatum Engl., P. myrmecophyllum Engl., P. pachyphyllum K. Krause, P. advena, and P. viride Engler. Most of these species are well known to me and are not believed to be closely related to those species with more or less oblong blades and purple-ringed petioles. Some of them may simply represent miscounts of ovule number per locule. For example, P. advena is reported by Krause as having one ovule per locule while the species is now known to have 1-4 ovules per locule. Philodendron subovatum is a synonym of P. advena. The latter is appropriately placed with P. sagittifolium in P. subsect. Macrobelium.

Philodendron smithii, the only other Central American species among those mentioned above, does indeed have tumid petioles and only a single ovule per locule like most members of P. subsect. Glossophyllum but the very great differences in leaf shape with this species and others placed here warrant their separation into another series within P. subsect. Glossophyllum (see below).

Though Krause's revision characterized P. subsect. Belocardium as having a single ovule per locule it is not in itself the defining feature of the subsection. For example, there are several species typical of the group with oblong leaves, purple-ringed petioles and the same general appearance which have more than one ovule per locule. These include: P. auriculatum, with (3)4 ovules per locule, P. ligulatum var. heraclioanum, and P. ligulatum var. ovatum (both with 2), P. pseudoauriculatum with 1-2(4) and P. wendlandii with 2 ovules per locule. Philodendron bakeri sometimes has two ovules per locule. Other Central American species, all each with one ovule per locule are P. brewsteriense, P. correae, P. dolichophyllum, P. folsomii, P. granulare, P. immixtum, P. ligulatum, P. morii, P. ubigantupense, and P. utleyanum.

Typical South American species in P. subsect. Belocardium presented by Krause (1913) are: P. longipetiolatum Engl., P. heterophyllum Poepp., P. uleanum Engl., P. adhatodifolium Schott, P. elaphoglossoides Schott, P. wittianum Engl., and P. angustialatum Engler. Philodendron tenuipes Engl., placed in P. subsect. Glossophyllum by Engler, appears to be closely related to P. fibrillosum and probably belongs in P. subsect. Canniphylla.

Other species described for P. subsect. Glossophyllum since the time of the last revision by Krause are P. acutifolium K. Krause, P. buntingianum Croat, P. liesneri Croat, and P. wurdackii G.S. Bunting. Though I have not seen the types of P. cyrtocoleum F. Diels and P. herthae K. Krause they appear also to be members of this group.

Though, as defined here, the P. subsect. Glossophyllum consists only of species with more or less oblong blades, some of the species are somewhat anomalous. Philodendron granulare is much like other species in P. subsect. Glossophyllum but it has a style that is unique in the group (Style Type E, see a discussion of this under that species). Both P. brewsteriense and P. ubigantupense are still very poorly known but appear to belong here. Perhaps the most doubtful is P. dolichophyllum which has 3-7 ovules which is certainly high for this group. However, it is otherwise similar in most aspects with other members of the subsection. Philodendron wendlandii, placed by Krause in P. sect. Baursia seems to fit best in P. subsect. Glossophyllum. It differs in having a petiole Glossophyllum which is usually broader than thick and sharply flattened adaxially and lacks an annular ring.