The bright orange-red or dark red flowers of Gladiolus decoratus are borne in a one-sided spike, from five to nine of them. The soft-textured floral bracts are narrow and pointed, dull grey-green in colour, sometimes reddish on a part of the outer one.
The funnel-shaped flower is laterally symmetrical. It has yellow or white streaks on the lower three tepals. The largest tepal, the upper or dorsal one is arched, up to 5,5 cm long.
The filaments and the branched style are arched under this tepal, well exserted. The fruit capsules to follow are ellipsoid, about 2,5 cm long (iNaturalist; JSTOR; www.mozambiqueflora.com).