Gladiolus

Gladiolus is a genus of mainly deiduous perennials growing from corms. Known and admired around the Mediterranean Sea for thousands of years, the Romans first called them Gladiolus, meaning small sword, referring to the sword-shaped leaves characterising the whole plant family, the Iridaceae.

During Simon van der Stel’s historic exploratory visit in 1685 to the copper mountains of Namaqualand many plants were collected. An artist, Claudius, who took part in that trip painted the first two recorded Gladiolus species encountered at the time. They were Gladiolus speciosus and G. caryophyllaceus, both initially named differently.

The corms or subterranean storage bodies of Gladiolus plants that render them perennial are derived from the globose internode part above the adventitious (and contractile) roots, below the annual stem. The usually white-tissued corm is symmetrical, surrounded by variously leathery to fibrous, protective layers of tunic, derived from three sheathing cataphylls and some basal leaves. The corm becomes active annually about three months before flowering.

The stems of Gladiolus plants, grown annually, are terete or compressed and angled, sometimes branched. From one to eight leaves, some basal and some cauline, i.e. up the stem, are grown. Leaf midribs, margins or some veins may be thickened, depending on the species.

Gladiolus inflorescences consist of simple or branched spikes, all flowers being sessile. Spikes are often secund (flowers facing to one side) and inclined. Every flower is subtended by an unequal pair of green or greenish bracts. The bisexual flowers are the most varied part in the Gladiolus genus, adapted to a range of pollinators.

These service providers that helped shape their clients and continue to do so are mostly bees, but also long-tongued flies, moths including hawk-moths, butterflies, wasps, birds and monkey beetles. Many gladioli also serve as larval food for Lepidoptera (moth and butterfly) species.

Laterally symmetric or zygomorphic flowers bearing arching style and stamens held together below the large dorsal tepal are the most common structure. Scattered species bear radially symmetric or actinomorphic perianths, the flowers star-shaped with equal tepals and stamens around central styles. In each flower there are six tepals in two whorls, three stamens, an inferior ovary and a three-branched style, sometimes with bilobed branch tips.

A sweet fragrance is often present in the usually pale-coloured, moth-pollinated species, sometimes intensified at night. Such species may close during the day, while others, inviting their pollinators in sunlight, close at night. Fragrance is probably produced in the papillae on the lower tepals and the upper part of the perianth tube.

The three-locular fruit capsules are often large, ellipsoid to ovoid in shape. The seeds are usually disc-shaped with a wing around the circumference, while in other species globose or angled, smooth or matte surfaced.

The genus consists of about 265 species of cormous perennials. About 170 of them occur in South Africa, while the centre of the genus diversity is in the Cape Floristic Region. The plants are generally semi-hardy in temperate regions. Many spectacular cultivars and hybrids exist beside some favoured species as garden subjects and for commercial cut flowers.

Flowering in many grassland species are fire adapted, prolific in new veld, particularly in the nutrient poor, winter rainfall region. Most species favour one particular soil type, referred to as edaphic fidelity, particularly where soils are strongly differentiated in texture and nutrients.

The plant in picture was thought to be G. filiformis, a little known and range restricted species of a part of North West and Botswana, but the flowers are very white, should apparently be light mauve, tinged lilac and bearing burgundy markings (Goldblatt and Manning, 1998; Leistner, (Ed.), 2000; http://www.abcjournal.org).