Peperomia membranacea is described as a fleshy herb with a unique growth pattern. The stems, which can be green or display a dark red hue towards the base, grow erect or ascend from a repent base, reaching lengths between 20 to 80 cm and diameters up to 10 mm at the base. These stems are few-branched in the upper part with internodes spanning 3–8(–15) cm and are consistently glabrous across their entirety. The leaf arrangement transitions from usually opposite in the lower part of the plant to typically whorled in the upper part. Leaves themselves are elliptic-lanceolate to ovate or elliptic-ovate, measuring (2.5–)4–9 cm in length and (1.5–)2–3(–4) cm in width, with acuminate to acute apices that slightly recurve and attenuate bases. The leaves have glabrous surfaces, with the upper side being dark green and the underside pale green, with a relatively thin and fleshy texture that dries to a membranous consistency. Margins are flat and may be sparsely ciliate towards the apex. The venation is palmately 5-veined, slightly impressed on the upper surface, and petioles are glabrous, ranging from 0.5 to 1.6(–2.5) cm long. Floral characteristics include spikes typically comprising 3–6 or more, spreading, axillary, and terminal clusters that may branch and extend 6–14 cm long, with lateral ones sometimes as short as 4 cm. Spaced along a glabrous rachis of 1.5–2 mm diameter, a peltate bract subtends the flowers and lack a perianth, making both calyx and corolla absent. Each flower contains two stamens, with the ovary being superior, broadly ovoid, 1-carpellate, and 1-celled. Fruits are broadly ovoid, about 0.8–0.9 mm long, with a slightly oblique beaked apex and a papillose-viscid surface covered in sessile glands. Each fruit contains a single seed, accompanied by scanty endosperm and abundant starchy perisperm. It is found in mesic to wet forests across between 240-1,740 meters,