Gladiolus (from Latin, the diminutive of gladius, a sword) is a genus of perennial bulbous flowering plants in the iris family (Iridaceae). It is sometimes called the ‘Sword lily’, but usually by its generic name (plural gladioli).

The genus occurs in Asia, Mediterranean Europe, South Africa, and tropical Africa. The center of diversity is in the Cape Floristic Region. The genera AcidantheraAnomalesiaHomoglossum, and Oenostachys, formerly considered distinct, are now included in Gladiolus.

The genus Gladiolus contains about 260 species, of which 250 are native to sub-Saharan Africa, mostly South Africa. About 10 species are native to Eurasia. There are 160 species of Gladiolus endemic in southern Africa and 76 in tropical Africa. The flowers of unmodified wild species vary from very small to perhaps 40 mm across, and inflorescences bearing anything from one to several flowers. The spectacular giant flower spikes in commerce are the products of centuries of hybridisation, selection, and perhaps more drastic manipulation.

Gladioli are half-hardy in temperate climates. They grow from rounded, symmetrical corms, that are enveloped in several layers of brownish, fibrous tunics.