This species is characterized by its medium-sized elliptic leaves, short racemiform inflorescences with 4-8 flowers borne on well developed pedicels 5-26 mm long, truncate calyx limbs, and red corollas with tubes 13-22 mm long and the fully reflexed lobes 8-20 mm long. The characteristic involucel or calyculus is borne at the base of the ovary, and is small (ca. 0.5 mm long) and shortly laciniate. Retiniphyllum laxiflorum is rather commonly collected. It is similar in general aspect to Ferdinandusa guainiae, with white corollas. 

Cortés-Ballén (2003) separated two varieties of Retiniphyllum laxiflorum, which differ in flower size and are widely separated geographically. Var. laxiflorum is by far the more widespread and commonly collected; var. brasilense is known only from the sandstone massif of the Chapada Diamantina in the interior of Bahia state in eastern Brazil.