Thesium lineatum, in Afrikaans the witstorm (white storm), is a root hemiparasite, a rigid, mostly leafless woody shrub reaching 1 m in height, occasionally higher and spreading. The plants are browsed, but toxic, particularly to sheep when flowering or fruiting.

The plant is mostly found in semi-arid westerly regions from Namibia and Namaqualand to the Little Karoo. It is seen among varied karoid vegetation types in loam and clay soils. The species is not considered threatened in habitat early in the twenty first century.

A root decoction is sometimes made for uses in traditional medicine (Vlok and Schutte-Vlok, 2010; iSpot; www.redlist.sanbi.org).