Gladioli grow from round, symmetrical corms^[7] (similar to crocuses) that are enveloped in several layers of brownish, fibrous tunics.^[8]

Their stems are generally unbranched, producing 1 to 9 narrow, sword-shaped, longitudinal grooved leaves, enclosed in a sheath.^[2] The lowest leaf is shortened to a cataphyll. The leaf blades can be plane or cruciform in cross section.

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 and selection.