Schiedea membranacea is a deciduous perennial herb that dies back to enlarged fleshy roots during dry seasons. It typically has swollen stems at the nodes, terete, 4-angled or 4-ridged, and ranges from 20 to 100 cm. These stems are usually multi-stemmed from the base, ascending to sprawling, often unbranched above, and predominantly purple in the internodes. The roots of the plant are notably fleshy and thickened. The leaves are simple and opposite, with broadly elliptic to broadly elliptic-ovate blades measuring 7 to 22 cm in length and 4 to 11 cm in width. The leaf apex is acuminate, and the base is broadly obtuse to truncate and somewhat folded. The upper surfaces of the leaves are glabrous, while the lower surfaces are sparsely puberulent, especially along the veins. The blades are thin or rarely slightly thickened and membranous, displaying a dull, dark green color. The margins are inconspicuously and irregularly serrulate, with more prominent teeth towards the apex. The plant typically has 5 to 7 conspicuous principal veins and petioles that are 0.3 to 2 cm long and weakly channeled, often purple. Stipules are absent. The inflorescence is terminal, bearing (28–) 100–205 flowers, and measures approximately 25 to 57 cm in length. The bracts are green and broadly ovate to ovate, with pedicels ranging from 10 to 35 mm long, elongating slightly in fruit. The flowers are bisexual (perfect), with 2 to 2.7 mm long sepals, ovate, and green turning purple. The corolla (petals) is absent. There are 10 stamens with dimorphic filaments and pale yellow anthers. The superior ovary is 1-celled, with free-central ovule placentation and 3 to 5 (sometimes 6) styles, often variable in number on the same plant. The fruit is a 2.5 to 3 mm long ovoid capsule with a purple apex. The seeds are highly variable in number, averaging 12 per capsule, and are approximately 0.8 to 1.0 mm long, orbicular-reniform, compressed. The perisperm (nutritive tissue surrounding the embryo) is starchy, with no true endosperm. It typically grows in rocky sites and at the bases of cliffs within mesic forests between 490-1,160 meters.