[1][2] Jens Klackenberg, the botanist who first formally described the species, named it after very narrow or thread-like (capillaceus in Latin) leaves.

The tips of the leaves are pointed and their margins are folded upwards at the base.

Its flowers have 5 broadly oval sepals that are 0.8–1 by 0.8–1 millimeters, with rounded tips and finely haired margins.

Its 5 violet petals are fused at the base forming a 0.5–0.7 millimeter long tube.

Its corona forms a short undulating ring with lobes between the stamens that are 0.4–0.5 millimeters high with rounded to truncated tops, as well as rectangular lobes opposite the stamens that are about the same size.