The false flowers or cyathia of Euphorbia perangusta are yellow. Inflorescences grow at stem-tips in erect cymes of about three cyathia, male and female ones next to each other on the same plant. The stalked fruits are brown-red and triangular, here appearing oblong.
Creamy yellow stem markings in regular patterns occur on the flat surfaces separating stem ridges. The angled out spine pairs on the stem ridges vary in size in particular sections. In picture large ones occur near the branching of the stem (Frandsen, 2017).