It is a low, spreading shrub, with linear leaves, and white or pale yellow flowers with 20 to 25 stamens.

The lower side of the leaves is deeply convex and grooved, with star-like oil glands.

[2][3][4] Hypocalymma tenuatum was first formally described in 2003 by Arne Strid and Greg Keighery in the Nordic Journal of Botany from specimens collected on Mount Lesueur in 1980.

[6] This species of Hypocalymma is found with laterite in wandoo woodland or on sandstone outcrops between the Lesueur National Park and Warradarge in the Geraldton Sandplains bioregion of south-western Western Australia.

[2][4] Hypocalymma tenuatum is listed as "Priority Two" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions,[2] meaning that it is poorly known and from one or a few locations.