The five petals are egg-shaped with the narrower end towards the base, dark red, 1.2–1.9 mm (0.047–0.075 in) long and glabrous.

Flowering occurs from July to October and the fruit is an oval capsule 2.5–3.0 mm (0.098–0.118 in) long.

[2][3] Lasiopetalum angustifolium was first formally described in 1904 by William Vincent Fitzgerald in the Journal of the West Australian Natural History Society from specimens he collected near Geraldton in 1903.

[6] This lasiopetalum grows in tall shrubland, scrub and heath in near-coastal areas from Shark Bay to near Perth and on a few off-shore islands.

[2][3] Lasiopetalum angustifolium is listed as "not threatened" by the Western Australian Government Department of Biodiversity, Conservation and Attractions.