This species is characterized by its thin-textured rather large ovate leaves with quite short petioles, slender flexuous inflorescences with the flowers subsessile in small subsessile groups, calyx lobes 0.2-3 mm long and are markedly unequal in size, white corollas with tubes 3-3.5 mm long, and rather small white fruits with 4 locules. Generally one calyx lobe is about twice as long as the others. The inflorescences are often quite long, with the flower-bearing portion up to 50 cm long.

Gonzalagunia sessilifolia similar to Gonzalagunia ovatifolia of Central America and northwesetern Colombia, and their separation probably deserves further study. Gonzalagunia ovatifolia is the older name; Ståhl (1999) treated this species as Gonzalagunia sessilifolia and did not discuss the Central America plants, similarly to Lorence et al. (2012) who treated the Central American plants as Gonzalagunia ovatifolia and did not resolve the status of the South American plants. Gonzalagunia sessilifolia is also similar to Gonzalagunia mildrediae of Amazonian Peru, which has corolla tubes 7-8 mm long and usually pedicellate flowers.