Helichryum platypterum is a perennial herb, erect or slightly decumbent, to ± 1 m tall, with a very hard woody tuber, up to 60 mm in diameter, with a single or several stems clumping together, the lower part leafy, the upper part slightly cobwebby.

Leaves are mostly 250 x 80 mm, becoming smaller up the stem, lower ones broadly elliptic, upper ones narrower elliptic to lanceolate, the base broad, clasping and extending downward in the winged stem, the tip acute with a small sharp point. Both surfaces have thin hairs, some of which are gland-tipped.

Flower heads are small, many, bell-shaped, ± 5 x 5 mm in a large spreading inflorescence, ± 200 mm across. Bracts are overlapping like tiles on a roof, inner ones more or less equalling in height the flowers. Flowers range from creamy white, white to creamy yellow, sweetly scented. Pappus bristles numerous, tips with short, stiff hairs. The flowering period is mainly between February and March, though some plants have been observed flowering in November and January.