Pelargonium desertorum is a summer deciduous, much branched, aromatic dwarf shrublet reaching 30 cm in height and spreading. The species was first collected in 1975 and described later.
The dark purple upper petal markings on the white corollas are notable. So are the pale, olive to purplish inside surfaces of the acutely pointed sepals.
The species distribution is small, restricted to mountainous areas near the Gariep River in the north of the Richtersveld and the south of Namibia.
The habitat is succulent Karoo veld on mountain tops and slopes. It favours south-facing slopes in granite-derived soils where rain falls in winter. The species is not considered to be threatened in its habitat early in the twenty first century (Williamson, 2010; iNaturalist; www.namibrand.com; http://redlist.sanbi.org).