Palicourea argentinensis is characterized by its strigillose to hirtellous or glabrescent pubescence on vegetative and reproductive structures; medum-sized petiolate leaves with elliptic blades; apparently laminar stipules with triangular to broadly triangular-ovate lobes 2-6 mm long; pedunculate, paniculiform inflorescences with linear bracts; deeply lobed calyx limbs 0.5-1 mm long; tubular-funnelform white corollas with the tube 5-7 mm long and the lobes with a rounded abaxial thickening; laterally flattened, ellipsoid fruits 4 × 4-5 mm; and pyrenes with well developed, rounded to acute abaxial ridges. The stipules are initially fused in a sheath that encircles the stem, but the intrapetiolar portion of the sheath is short and often pulls apart or shrinks with age and can be difficult to see on many stipules. The inflorescences are often cylindrical in outline and apparently racemiform when young, due to their relatively short, ascending secondary axes, but as axes develop they spread and elongate to produce a pyramidal form. The bracts subtending the flowers are not regularly developed, but each cyme has a few distinctive narrow bracts 1-3 mm long. The calyx limb varies from short (ca. 0.8 mm long) with triangular acute lobes, to well developed (ca. 1.5 mm long) with ovate, acuminate, aristate lobes. The corolla tubes are slender and weakly swollen at the base, and glabrous internally except for a pilosulous band near the middle. Externally the corollas vary from pilosulous to glabrous. Palicourea argentinensis has one of the southernmost ranges in the genus, into the Tucumano forest and northern Argentina.