1. Family: Geraniaceae Juss.
    1. Genus: Pelargonium L'Hér. ex Aiton
      1. Pelargonium acetosum (L.) L'Hér.

        There are around 280 species of Pelargonium, over 200 of which are native to South Africa. These attractive plants have long been prized by gardeners, and some were brought to Europe at a surprisingly early date. Pelargonium acetosum, for example, was growing in the medicinal plant garden in Amsterdam by 1703 and in the Chelsea Physic Garden by 1724.

    [KSP]

    Kew Species Profiles

    General Description
    Originating in South Africa, the sorrel-leaved pelargonium is an elegant evergreen with a long flowering season that has been grown in England since 1724.

    There are around 280 species of Pelargonium, over 200 of which are native to South Africa. These attractive plants have long been prized by gardeners, and some were brought to Europe at a surprisingly early date. Pelargonium acetosum, for example, was growing in the medicinal plant garden in Amsterdam by 1703 and in the Chelsea Physic Garden by 1724.

    Originally described in 1753 as Geranium acetosum by the Swedish botanist and 'father of taxonomy' Carl Linnaeus, the name was changed to Pelargonium acetosum by the French botanist Charles Louis L'Héritier de Brutelle in 1789.

    Unlike many other pelargoniums, this species does not have attractively scented leaves. The epiphet acetosum is Latin for 'sour' and refers to the acid taste of the leaves.

    Species Profile
    Geography and distribution

    Native to the south-eastern Cape in South Africa, with isolated localities near Uitenhage and in Orange Free State.

    Description

    Overview:   Pelargonium acetosum is a glaucous, succulent, much-branched shrub up to 60 cm tall and wide. 

    Leaves:  Its irregularly lobed leaves are smooth, fleshy, greyish-green with red margins and borne on slender branches. When crushed, the leaf smells and tastes acidic, like common sorrel ( Rumex acetosa ).

    Flowers: Its five-petalled flowers are 5 cm across, usually salmon-pink but also in paler shades, and borne throughout much of the year on long stiff stems.

    Threats and conservation

    Though this species is common in many areas of the south-eastern Cape, it is vulnerable to grazing by goats.

    Uses

    Sorrel-leaved pelargonium is grown as an ornamental. The buds and young leaves are eaten in South Africa. They have a bitter taste but can be eaten raw in salads or added to soups and stews.

    Millennium Seed Bank: Seed storage

    The Millennium Seed Bank Partnership aims to save plant life worldwide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in Kew's seed bank vault at Wakehurst.

    Description of seeds: Average 1,000 seed weight = 7.31 g

    Number of seed collections stored in the Millennium Seed Bank: One

    Seed storage behaviour: Orthodox (seeds of this plant survive drying without significant reduction in their viability and are therefore amenable to long-term frozen storage such as at the MSB)

    Germination testing: 90% germination on 1% agar at 20°C, on a cycle of 8 hours daylight / 16 hours darkness. The pre-sowing treatment included seed scarification (chipping with scalpel).

    Cultivation

    Pelargonium acetosum is grown in sandy soil. It should be kept dry, especially in winter, and free from frost. It roots easily from cuttings.

    Pelargoniums at Kew

    In 1789, William Aiton listed 102 species of Pelargonium in his book Hortus Kewensis (a publication listing all species being grown at the Royal Botanic Gardens, Kew at the time), and the genus subsequently became incredibly popular amongst British gardeners.

    This species at Kew

    Sorrel-leaved pelargonium is growing in the Princess of Wales Conservatory in the dry climate section.

    Pressed and dried specimens of Pelargonium acetosum are held in Kew's Herbarium, where they are available to researchers from around the world, by appointment. The details of some of these, including images, can be seen online in the Herbarium Catalogue.

    Distribution
    South Africa
    Ecology
    Dry cliffs, rocky slopes, dry grassland.
    Conservation
    Least Concern (LC) according to Red List of South African Plants 2009, following IUCN Red List criteria.
    Hazards

    Pelargoniums can cause mild skin dermatitis.

    [KSP]
    Use
    Ornamental, young leaves and buds edible.

    Images

    Distribution

    Native to:

    Cape Provinces

    Common Names

    English
    Sorrel-leaved pelargonium

    Pelargonium acetosum (L.) L'Hér. appears in other Kew resources:

    Date Reference Identified As Barcode Type Status
    Nov 4, 2005 coll. ign. [s.n.] K000351646
    MacOwan, P. [425/413], South Africa K000417308
    Goodenough [s.n.], South Africa K000417307

    First published in W.Aiton, Hort. Kew. 2: 430 (1789)

    Accepted by

    • Germishuizen, G. & Meyer, N.L. (eds.) (2003). Plants of Southern Africa an annotated checklist Strelitzia 14: 1-1231. National Botanical Institute, Pretoria.

    Literature

    Kew Species Profiles
    • The Plant List (2010). Pelargonium acetosum.
    • Raimondo, D. et al. (2009). Red List of South African Plants 2009. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
    • Phillips, R. & Rix, M. (1997). Conservatory and Indoor Plants, Vol. 1. Macmillan, London.
    • Miller, D. (1996). Pelargoniums. Batsford, London.
    • Bown, D. (1995). The Royal Horticultural Society Encyclopedia of Herbs & their Uses. Dorling Kindersley, London.
    • Kunkel, G. (1984). Plants for Human Consumption: an Annotated Checklist of the Edible Phanerogams and Ferns. Koeltz Scientific Books, Koenigstein.
    • Van der Walt, J.J.A. illus. E. Ward-Hilhorst (1979). Pelargoniums of Southern Africa. Vol. 1. Fischer, Hillscheid & Cape Town.
    Kew Backbone Distributions
    • Germishuizen, G. & Meyer, N.L. (eds.) (2003). Plants of Southern Africa an annotated checklist Strelitzia 14: 1-1231. National Botanical Institute, Pretoria.

    Sources

    Herbarium Catalogue Specimens
    'The Herbarium Catalogue, Royal Botanic Gardens, Kew. Published on the Internet http://www.kew.org/herbcat [accessed on Day Month Year]'. Please enter the date on which you consulted the system.
    Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

    Kew Backbone Distributions
    The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Kew Names and Taxonomic Backbone
    The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Kew Species Profiles
    Kew Species Profiles
    http://creativecommons.org/licenses/by-nc-sa/3.0