Its scientific name means “low-lying sword plant”, which only refers to its decumbent, i.e. creeping flower stalks; the leaf rosette has an upright growth habit.
E. decumbens is closely related to E. subalatus, and its emersed form differs from it – amongst other characteristics – by its decumbent (instead of upright) flower stalks, which grow distinctly larger than the leaves and whose flower whorls grow at larger distances. Its lanceolate leaves are generally narrower than those of E. subalatus. Its flower stalk axils are triangular, but not alate like those of E. subalatus.