[3] Isaac Bayley Balfour,[4] the naturalist who first formally described the species named it, using the synonym Tanulepis sphenophylla, after its wedge-shaped leaves (Latinized forms of Greek σφην-, sphen- and φύλλον, phúllon).

Its inflorescences occur at the junction between the leaves and stem and have sparse flowers.

Its flowers have 5 small sepals that are 1 millimeter long, fused at their base, with triangular lobes.

Its 5 hairless, greenish petals are fused at the base, 3.1 millimeters long, with lance-shaped lobes.

Its anthers and stigma are fused to form a structure called a gynostegium that is 1 by 1 millimeters Its smooth, cylindrical fruit are up to 7.6 centimeters long with pointed tips.