Gladiolus is a large genus of around 180 species of perennials that grow from corms. Many originate from the rocky slopes, seasonally dry grassland and marshy areas of South Africa, and are grown for their spikes of showy funnel-shaped flowers that open from the bottom upwards. Over 10,000 hybrids and cultivars have been developed for cultivation, exhibiting and cutting. They are classified into 3 groups - Grandiflorus, Nanus and Primulinus. Grandiflorus produce one spike per corm that has closely packed flowers and up to 28 buds of which 12 open at any one time. These are further divided into 5 size classes, according to the diameter of the bottom flower. Nanus hybrids and cultivars produce 2-3 slender spikes with loosely arranged flowers, bearing up to 7 buds, with 3-5 open at one time. Primulinus hybrids and cultivars produce only one thin whip-like stem per corm which bears as many as 23 buds, with up to 7 open at a time. The flowers arranged in a semi-formal step-ladder arrangement. A favourite with many gardeners and exhibitors, Gladioli - or Sword Lilies, as they're sometimes known - can be grown in clumps in borders, or in rows for cutting. They like a sunny site with well-drained, fertile soil. The corms can be lifted and new ones stored over winter, or they can be left in the soil and more tender ones mulched, to protect them from frost in cool climates. Depending on the group they belong to, they will flower at different times throughout the summer.