Berkheya purpurea (purple berkheya)
Berkheya purpurea flowers
Berkheya purpurea (DC.) Mast.
purple berkheya, African thistle
Least Concern (LC) according to Red List of South African Plants 2009, following IUCN Red List criteria.
Beside streams and on steep, grassy mountain slopes.
About this species
There are about 75 species of Berkheya, a genus of shrubs and perennials distributed throughout tropical Africa, and named after the Dutch botanist Jan le Francq van Berkhey (1729–1812) by the German botanist Jakob Friedrich Ehrhart in 1788. Over 70 species are native to South Africa, where they grow mainly on mountain slopes.
Berkheya purpurea is the only mauve to purple flowered species in the genus (most are yellow or occasionally white), and was first described in 1838 by the French botanist Augustin Pyramus de Candolle, who named it Stobaea purpurea. It was renamed Berkheya purpurea in 1872.
Stobaea purpurea DC., Crocodilodes purpureum (DC.) Kuntze
Geography and distribution
Berkheya purpurea is found in South Africa at elevations of 1,500–3,000 m from the mountains of the Eastern Cape to the Drakensberg in KwaZulu-Natal and also in Lesotho and Orange Free State.
Overview: Berkheya purpurea is a rhizomatous perennial forming a dense prickly rosette of foliage.
Leaves: The leaves measure 25–45 cm long and 4–10 cm wide and are green on the upper side, downy on the underside with spiny margins.
Flowers: The single flowering stem, up to 1 m high, appears from December to April in the wild and June to August in cultivation. The flower heads (capitula) are carried on short side branches on the upper part of the flowering stalk, and the buds open in succession from the top of the stem downwards. Several capitula may open simultaneously. Each capitulum has a ring of pale mauve outer ray florets with central dark purple disc florets, although occasionally the ray florets may be white. A circle of spiny green bracts (phyllaries) protects the capitula.
Fruits: The pappus (scales surrounding the apex of the fruit) is light green at first and then turns light to dark brown as the fruits (achenes) mature.
The flowers are pollinated by bees.
Purple berkheya is cultivated as an ornamental.
Berkheya purpurea was apparently grown at Kew around 1917 but has only recently become popular in gardens in Britain; it is now available from commercial seed companies.
In Britain, plants raised from seed (ideally sown after collecting in the autumn or delayed until the following spring) are planted out in the garden in spring. They grow best in well-drained soil and full sun. They look good in groups and planted among low grasses, as seen in the wild.
Berkheya purpurea is also propagated by division of the rootstock.
This species at Kew
Purple berkheya can be seen growing in the Rock Garden at Kew, and in the South African Bed of the Southern Hemisphere Garden at Wakehurst.
Pressed and dried, and alcohol-preserved specimens of Berkheya purpurea are held in Kew’s Herbarium, where they are available to researchers from around the world, by appointment. The details of some of these specimens, including images, can be seen online in the Herbarium Catalogue.
Illustration from Curtis's Botanical Magazine
Curtis’s Botanical Magazine (Editor: Martyn Rix) provides an international forum of particular interest to botanists and horticulturists, plant ecologists and those with a special interest in botanical illustration.
Now well over 200 years old, the Magazine is the longest running botanical periodical featuring colour illustrations of plants. Each four-part volume contains 24 plant portraits reproduced from watercolour originals by leading international botanical artists. Detailed but accessible articles combine horticultural and botanical information, history, conservation and economic uses of the plants described.
Published for the Royal Botanic Gardens, Kew by Wiley-Blackwell Publishing.
Hind, D.J.N. (2006). Berkheya purpurea. Curtis’s Botanical Magazine 23: 289-296.
Raimondo, D. et al. (2009). Red List of South African Plants 2009. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
The Plant List (2010). Berkheya purpurea. Available online (accessed 24 September 2011).
Kew Science Editor: Martyn Rix and Nicholas Hind
Copyediting: Malin Rivers
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