A smaller plant, Gasteria armstrongii, which occurs just to the west on the banks of the Gamtoos river, is often considered to be a subspecies of G.nitida, which never leaves its juvenile phase (a possible case of neoteny).

The armstrongii plant has rough, tuberculate, recurved, purely distichous leaves, and a solitary unbranched inflorescence.

This species occurs over an extensive coastal range of the Eastern Cape Province, South Africa, from Uniondale in the west, as far as the Fish River in the east.

Here it occurs on rocky hill slopes in grassland vegetation - one of the few Gasterias to favour an open habitat.

The soil tends to be coarse, mineral poor sands, derived from the quartzite sandstones of the region.