A robust, deciduous, winter-growing, perennial geophyte, 300–600 to 1 200 mm tall. Rootstock is a globose, papery corm, with membranous tunics, 14–20 mm in diameter. The stem is slender and erect, branched, 2.5–4 mm in diameter and about 500 mm long. Leaves are sword-shaped, flat, firm, linear and differ in length according to species. Gladiolus angustus has 4 or 5 leaves with 2 or 3 basal leaves, the longest reaching or shortly exceeding the flower spike. Blooms in spring to early summer, from October to November, bearing 3 to 6 flowers in a lax spike. Flowers are cream- to pale cream-coloured, sometimes flushed with pink, with a bright reddish purple, spade-shaped marking in the midline of the 3 lower lobes. The perianth tube is slender, 50–110 mm long, much longer than the tepals which are 16–18 mm long, lanceolate and unequal. Seeds are broadly winged and ovate, the seed body slightly brown.