Poranthera microphylla is a decumbent or more or less upright, slender, densely branched, annual herb up to 30 cm (12 in) high.

It has soft, smooth branches, egg to spoon-shaped blue-grey leaves, thin, usually 4–15 mm (0.16–0.59 in) long, 8–15 cm (3.1–5.9 in) wide, margins more or less flat or slightly recurved, petiole 2–5 mm (0.079–0.197 in) long, apex blunt or rounded and mostly with a short, triangular point.

Flowering occurs mostly from September to April and the fruit is a 3-lobed capsule 1.5–2 cm (0.59–0.79 in) in diameter, white and warty.

[2][3] Poranthera microphylla was first formally described in 1833 by Adolphe-Théodore Brongniart and the description was published in Annales des Sciences Naturelles.

[5] Small poranthera is a widespread species and grows in dry, montane forest, woodland and grassland in New South Wales, Victoria, Western Australia, Tasmania, Queensland and the Australian Capital Territory.