Ornithogalum sardienii is a tiny plant growing from a small bulb positioned above-ground. The plant only reaches 5 cm in height when its flowers are present.
The inflorescence is a lax raceme, individual flowers growing on long pedicels. The white star-shaped flowers have six spreading tepals, the corolla smaller than 1 cm in diameter. There may be green patches on the inside surfaces near the tips of the narrow tepals. Six spreading stamens around the superior, green ovary bear pale yellow, globular anthers. Flowering happens in summer.
This Ornithogalum is endemic to a small distribution in the Little Karoo between Calitzdorp and De Rust. This couple of plants were found growing exposed on a stony, bare hillside south of Oudtshoorn.
The plants form clumps under shrubs in semi-arid conditions in gravelly soils. The species is critically rare, but not considered threatened in habitat early in the twenty first century (Vlok and Schutte-Vlok, 2010; www.redlist.sanbi.org).