Cormous geophyte up to 1.2m. Leaves sword-shaped, often with a waxy bloom, 12-20mm wide. Flowers scarlet in elongate, usually branched spike; perianth tube 36-44mm long, tubular above; stamens arcuate (curved upward like a bow); bracts mostly 9-14mm long.

Capsules narrowly spindle-shaped, tapering to a narrow tip.

Corms of this species are often scratched up as food (Afrikaans 'kos' = food) by partridges (Afrikaans = Patryse).

After: Sir William Watson (1715-1787), London physician, apothecary, botanist, Fellow of the Royal Society. He helped to introduce the ideas of Carl Linnaeus to England.