Plant 311

Pelargonium species (Geraniaceae)


Pelargos is Greek for stork and, as the seed capsule of the pelargonium resembles the beak of a stork, this was used in the generic name Pelargonium. The genus comprises more than 280 species that are native to Africa, the Atlantic Islands, Australasia and temperate Asia. Pelargonium species are commonly called geraniums, but they must not be confused with the genus Geranium, which is generally a hardier herbaceous plant, in the same family. Pelargoniums were originally included in the genus Geranium by the Swedish naturalist Carolus Linnaeus but, in 1789, the French botanist Charles L'Héritier separated the two genera. The naming has strong links with Oxford as it was Johann Jacob Dillenius, the first Sheradian Professor of Botany at Oxford, who in 1732, first proposed the separation and the name Pelargonium.

Pelargonium species have been in cultivation in European gardens since the early seventeenth century. Indeed, the 1648 catalogue of plants being grown in Oxford Botanic Garden, included a Pelargonium species. Today, a collection of Pelargonium species is grown in the Garden, including Pelargonium sidoides. This species has small black flowers and silvery leaves and currently grows outside all year round in a sunny, well-drained border.

However, most Pelargonium species need winter glasshouse protection. For example, Pelargonium tomentosum, with gloriously velvety leaves, smelling of peppermint and Pelargonium tongaense with bright red flowers, a species only described in 1983 and considered rare in the wild as it is found in only a small area of northeast Natal. During the nineteenth century some Pelargonium species were used in hybridisation to produce hundreds of cultivars, many of which are still grown today, for example, Pelargonium 'Caroline Schimidt', Pelargonium 'Crystal Palace Gem' and Pelargonium 'Distinction'. Pelargonium inquinans and Pelargonium zonale are two species that have been used to create the zonal pelargoniums that we know today.

Pelargoniums can be a subshrub, herbaceous perennial or annual, with some being over two metres tall. Some species have thick succulent stems for water storage, such as Pelargonium cotyledonis, a species from the island of St. Helena. Many pelargoniums grown in gardens are classed as herbaceous perennials and do not like wet, cold or frosty conditions. These have been put into groups such as Scented-leaved, Unique, Regal, Ivy-leaved and Zonal. A sunny, well-drained spot is best, although they can be grown in containers. Propagation is easily done by cuttings, but pests such as whitefly can be a problem.

Further reading

Huxley, A 1999. The New Royal Horticultural Society dictionary of gardening. Groves Dictionaries Inc.

Sajeva M and Costanzo M 1995. Succulents: the illustrated dictionary. Cassell plc.

Lucinda Lachelin