This species is characterized by its usually somewhat narrow leaves with the distinctive venation of Sect. Tricephalium, its bilobed stipules, its capitate or shortly branched small inflorescences that are pedunculate and have small bracteate heads, and its rather small fruits. The inflorescences are variously borne in a terminal position, in the axils of the uppermost leaves, and/or on paired short lateral stems at lower leaf nodes. The inflorescences that are produced at lower leaf nodes have sometimes been considered axillary, but are considered terminal on short stems. Palicourea sessilis is similar to Palicourea jungiana and Palicourea oxapampana. As circumscribed here and by most previous authors, Palicourea sessilis includes a notable amount of morphological variation. Probably more than one species is included here, but more detailed study including field observations will be needed to understand the taxonomy of these plants.

Two subspecies are separated provisionally in Palicourea sessilis. Palicourea sessilis subsp. sessilis is found in Brazil and includes nearly all the plants of this species, while Palicourea sessilis subsp. sororopanensis is found in a disjunct range in the Guayana Highlands and is not well known. No morphological distinctions are evident at present between these two groups of plants, so they are here included in the same species but separated based on their geographic range. It is possible that better documentation of the Guayana region plants will clarify that they belong to a separate species. Palicourea oxapampana represents a similar case to Palicourea sessilis subsp. sororopanensis, but Palicourea oxapampana differs morphologically as well as in range from Palicourea sessilis and thus is recognized as a distinct species.

• Taylor, C. M. 2015. Rubiacearum americanarum magna hama pars XXXIV: The new group Palicourea sect. Tricephalium with eight new species and a new subspecies (Palicoureeae). Novon 24(1): 55–95.