Watsonia is a genus of plants in the iris family, subfamily Crocoideae, native to South Africa. The genus is named after Sir William Watson, a British botanist. There are 52 species in southern Africa; all are perennial herbs growing from corms and producing erect spikes of showy flowers, and are adapted to a mediterranean-type climate. The most common species in cultivation is the pink-flowered Watsonia borbonica and its white mutant ‘Arderne’s White’. These were crossed with Watsonia meriana and other species in the early 20th century by breeders including John Cronin in Australia and Luther Burbank in California to produce a wide range of cultivars. Watsonia has been eclipsed in popularity by Gladiolus and other bulbs, and is now neglected by the nursery industry. In the South-West of Western Australia, six species have become naturalised from garden escapes along rivers, wetlands and seasonally wet ground.

Watsonia marlothii is a South African endemic perennial geophyte found in the Western Cape province. It grows from 60cm to 120cm and is found on rocky sandstone slopes in fynbos in the Swartberg Mountains. It has sword-shaped leaves with thickened margins and midrib and red to pink flowers in an elongate spike. It flowers November to January.