The flowers are arranged in toothbrush-like racemes along a rachis usually 30–50 mm (1.2–2.0 in) long, and are purplish with grey or white hairs.

[4][5][6][7][8] G. aspleniifolia closely resembles its relative, G. longifolia but differs in that its branchlets are rounded and covered in short, grey wooly hairs, whereas the branchlets of G. longifolia are ruddy brown and covered in brownish, appressed hairs.

[8][9] Grevillea aspleniifolia was first formally described in 1809 by Joseph Knight in On the cultivation of the plants belonging to the natural order of Proteeae.

[6] This grevillea grows in woodland on sandstone or shale in the catchments of the Warragamba Dam and Woronora River, and near Bungonia Caves, in eastern New South Wales.

Threats to this species include damage and/or grazing by introduced deer and changed fire regimes.