Hyalosperma demissum, commonly known as moss sunray,[2] is a flowering plant in the family Asteraceae.

It is a small, annual herb with whitish yellow flowers and is endemic to Australia.

Hyalosperma demissum is a rounded, small annual to 5–20 mm (0.20–0.79 in) high and sparsely covered with long, soft, straight hairs or smooth.

The whitish-yellow flowers are in dense clusters amongst the foliage, the bracts are arranged in 3-4 rows, broadly oblong to oval shaped, outer bracts 2–2.5 mm (0.079–0.098 in) long, almost translucent, light green, silvery or light yellowish brown.

Flowering occurs from September to December and the fruit is a dry, one-seeded, compressed, egg-shaped, warty and about 0.7 mm (0.028 in) long.