Berkheya purpurea

Berkheya purpurea, nicknamed South African Purple Thistle, is one of those unusual large perennials with a wild charm that give a special touch to the garden of a curious person. Resembling a thistle, it is botanically closer to Arctotis and Gazania. It develops a persistent rosette composed of long, grey-green, spiny, fuzzy leaves, from which tall, branched stems emerge in summer, bearing large inflorescences resembling pale purple daisies around a purplish centre. Relatively hardy in well-drained soil, it will self-seed freely in a garden that makes room for nature, in a large rockery, near a pathway, or in a sunny flower bed.

Berkheya purpurea is a plant in the Asteraceae family, native to cool high-altitude grasslands in eastern South Africa. Its natural habitat is a large, moist, rocky escarpment along watercourses, in a cold and occasionally hot and dry climate. This plant is therefore capable of adapting to our climates, mountainous or coastal, with a few waterings if the summer is dry. As an adult, the purple thistle will reach a height of 90cm (35in) when in bloom, 30cm (12in) for the foliage, and 50cm (1 and 20in) in width. Its growth is rapid, and its longevity is quite remarkable in favourable soil. Its leaves form a dense basal rosette. They are long and narrow, thick, upright, pale silver-green, shiny, and edged with spiny teeth. Their undersides are fuzzy. The main attraction of this plant is its flowering, in the form of large 8-10cm (3-4in) diameter heads. The inflorescence consists of a crown of green, spiny bracts supporting the collar of pale mauve-lilac ligules arranged around a centre of purple florets, dusted with white pollen. Each basal rosette produces a single thick stem adorned with small leaves, which branches out and carries between 10 and 15 inflorescences at the same time. Their lifespan does not exceed a few days. They are heavily visited by bees and butterflies, as well as numerous pollinating insects. The flowering is followed by the formation of numerous seeds that easily germinate in light soil.

This purple thistle is a plant that inspires admiration or arouses curiosity, better suited to a country garden or a natural rockery than to an urban garden where each element is precisely placed in a limited space. In fact, this Berkheya self-seeds wherever it finds the slightest crack within reach of a seed. It is simply stunning in steep hillside or mountain gardens, in the company of blue delphiniums, Aconitum, and pink or purple roses in moist soil, but also blends well with giant grasses (Panicum virgatum, Miscanthus sinensis), Agapanthus, Grevillea, Callistemon, Cistus, lavenders, and rosemary or tall mulleins in drier gardens.