 "Vermilacinia rigida" is classified in the subgenus "Vermilacina" in which it is distinguished by the thallus divided into short rigid erect branches blackened to about ¼ the way up from the base.The branches are strongly compressed, resembling short grass-like blades, 0.5 to 2 cm high and 1–4 mm wide.Lichen substances are primarily the diterpene (-)-16 α-hydroxykaurane, with trace amounts of zeorin, or zeorin lacking, and two other unknowns, one of which is referred to as the T4 compound that is found in "V. combeoides" and "V. pumila".