Edmondia sesamoides is a perennial shrublet, with a slender erect growth form up to 300 mm tall. Stems are thinly white-woolly and sparsely-branched. The leaves are dimorphic (with two different forms), at the base of the plant on the vegetative stems the leaves are very narrow and linear and 20–50 mm long, but on the flowering shoots they are short, 5–10 mm long, clasping and adpressed to the stem. Leaves have white hairs on the upper surface and are shiny and hairless below. Towards the tips of the flowering shoots the leaves give way to brown papery bracts and then to the solitary conical papery flowerheads which are ~25 mm long and ~50 mm across. Each flowerhead, called an inflorescence, has several closely overlapping papery bracts which resemble petals, surrounding a dense cluster of tiny yellow or brownish-yellow flowers. The bracts are narrowly pointed and range in colour from silvery-white to pale yellow to pink. Flowering is in late winter, spring and early summer (from August to December). Each flower produces a tiny cylindrical fruit topped by a tuft of pappus bristles.

Edmondia as a whole is often confused with the related genera Syncarpha and Helichrysum. The dimorphic leaves, long linear leaves at the base of the plants and short clasping leaves towards the flowerheads, distinguishes Edmondia from these related genera, where leaves are typically similar throughout the plant. Similarly, the leaves of Edmondia species are involute, with margins curled upwards, towards the top of the leaf whereas Syncarpha and Heliychrysum leaves are typically revolute, curled downwards, towards the bottom.

The genus contains only three species, Edmondia sesamoides, E. pinifolia and E. fasciculata which are easily confused. E. sesamoides differs from E. fasciculata by having brown scaly bracts only immediately below the head, whereas in the latter species these continue for 20–50 mm below the heads. It differs from E. pinifolia by having cylindrical as opposed to flattened fruits.