There are 5 linear to tapering triangular sepals which are mostly 9–12.5 mm (0.4–0.5 in) long with their outer surface densely covered with a thick layer of woolly hairs.

Flowering occurs from June to September and is followed by oval-shaped fruits which have a crusty, woolly covering and are 6–7 mm (0.2–0.3 in) long.

[3][4]Eremophila lachnocalyx was first formally described in 1942 by Charles Gardner and the description was published in Journal of the Royal Society of Western Australia.

It occurs in scattered populations between Sandstone, the Barlee Range and Karijini National Park in the Gascoyne, Murchison and Pilbara biogeographic regions.

[6] Its silvery-grey foliage and masses of cottony buds followed by pale lilac-coloured to purple flowers make this one of the most attractive eremophilas.