It is a spiny, sprawling shrub with narrowly elliptic leaves clustered around spiny side-shoots, flowers with relatively large sepals, five spreading white petals and five stamens, and concave fruit.

Bursaria longisepala is a spiny, sprawling shrub that typically grows to a height of less than 1 m (3 ft 3 in), some stands retaining juvenile characteristics.

The sepals are larger in this species than in others of the genus, green or cream-coloured, 3.5–4.0 mm (0.14–0.16 in) long, free from each other and spreading from the base.

[2][3] Bursaria longisepala was first formally described in 1926 by Karel Domin in the journal Bibliotheca Botanica from specimens he collected in the Blue Mountains in 1910.

[4] This bursaria mostly grows on south-facing cliffs and in disturbed areas in forest and woodland and is mainly found in the Blue Mountains and sometimes on the central coast of New South Wales.