Centaurea cyanus, the cornflower, is a sturdy border plant with blooms of pure blue, pink or white that make excellent cut flowers.

The most popular annual zinnia, Zinnia elegans, is native to Mexico; the vivid colours of its luxurious blooms certainly have an exotic air.

The garden relatives of the common Narrow bear yellow or white flowers in flattened clusters. With fern-like, grey-green leaves, they are handsome additions to the summer border.

Salpliglossis sinuata is such an exotic-looking plant that it is difficult to believe it is so easy to grow - or that it belongs to the same family of plants as the potato.

Native to Europe and Western Asia, this group of herbaceous perennials includes three species which are well suited to summer borders or informal planting schemes.

Verbena peruviana, a native of South America, is a low growing perennial that looks best where its tiny though startlingly bright red flowers can spill over a sunny wall. It does well in a sheltered rock garden or a stone trough in a favoured corner.

The sweet pea, Lathyrus odoratus, climbs by means of leaf tendrils. Its wing-petalled flowers are coloured white, pink, red, lilac or cream, and are sometimes strongly scented. They are extremely popular as cut flowers.

The euphorbia family comprises a great many plants including annuals and shrubs. Among the evergreen perennials E. robbiae is particularly attractive, with upright stems, whorls of dark green leaves and loose heads of lime-green flowers and bracts.

There are several species of trollius, the globe flower, in cultivation, all bearing impressive rounded blooms in various shades of yellow with prominent stamens.

Bees and butterflies are irresistibly attracted to the vivid, shaggy flowers of Monarda didyma, a highly decorative relative of mint which is variously known as bee balm or Oswego tea. Native to North America.