Gladiolus

Gladiolus — Gladiolus (from Latin, the diminutive of gladius, a sword) is a genus of flowering plants in the iris family (Iridaceae). Sometimes called the sword lily, the most widely-used English common name for these plants is simply gladiolus (plural gladioli or gladioluses).

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 species vary from very small to the spectacular giant flower spikes in commerce.

These attractive, perennial herbs are semihardy in temperate climates. They grow from rounded, symmetrical corms, that are enveloped in several layers of brownish, fibrous tunics.

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

The fragrant flower spikes are large and one-sided, with secund, bisexual flowers, each subtended by 2 leathery, green bracts. The sepals and the petals are almost identical in appearance, and are termed tepals. They are united at their base into a tube-shaped structure. The dorsal tepal is the largest, arching over the three stamens. The outer three tepals are narrower. The perianth is funnel-shaped, with the stamens attached to its base. The style has three filiform, spoon-shaped branches, each expanding towards the apex.

The ovary is 3-locular with oblong or globose capsules, containing many, winged brown, longitudinally dehiscent seeds.

These flowers are variously colored, pink to reddish or light purple with white, contrasting markings, or white to cream or orange to red.

The South African species were originally pollinated by long-tongued anthrophorine bees, but some changes in the pollination system have occurred, allowing pollination by sunbirds, noctuid and sphingid moths, long-tongued flies and several others.

Gladioli are used as food plants by the larvae of some Lepidoptera species including the Large Yellow Underwing.

Gladioli have been extensively hybridized and a wide range of ornamental flower colours are available from the many varieties. The main hybrid groups have been obtained by crossing between four or five species, followed by selection: Grandiflorus, Primulines and Nanus. They make very good cut flowers. However, due to their height, the cultivated forms frequently tend to fall over in the wind if left on the plant.

In temperate zones, the corms of most species and hybrids should be lifted in autumn and stored over winter in a frost-free place, then replanted in spring. Some species from Europe and high altitudes in Africa, as well as the small ‘Nanus’ hybrids, are much hardier (to at least -15°F/-26°C) and can be left in the ground in regions with sufficiently dry winters. Plants are propagated either from small cormlets produced as offsets by the parent corms, or from seed; in either case, they take several years to get to flowering size.