Roscoea purpurea (bhordaya)
Roscoea purpurea is a vigorously growing plant with flowers in a wide variety of colours, usually purple, but also pink, white and rarely bright red.
About this species
Roscoea is a genus of 22 species belonging to the ginger family (Zingiberaceae), and occuring in the Himalaya. Roscoeas have fleshy roots that are dormant in winter. They are hardy in many regions but have delicate, orchid-like flowers that appear in mid-summer.
Roscoea purpurea was the first Roscoea species to be described around 1806 from specimens collected in Nepal by the Scotsman Francis Buchanan, who collected and described many new plants from India and Nepal. The genus is named after William Roscoe (1753–1831), who founded Liverpool’s first botanic garden in 1803 and had an interest in gingers.
Geography & Distribution
Native to the Himalaya from central India (Himachal Pradesh) to Nepal and the Bhutan–Assam frontier, between 1,500-3,100 m elevation.
Roscoea purpurea has fleshy roots. The leaves (4–8) are soft and somewhat wavy, bright green, smooth or ciliate, 14–20 cm long and held horizontally or recurved. The leaf sheaths are often purple or reddish. The bracts are narrowly ovate and mostly hidden by the upper leaves.
The flowers are purple, mauve, red or white and appear in succession from among the upper leaves from June to September. Each flower only lasts one or two days. The floral tube is 6.5–10 cm long, but hidden by the bract and upper leaf sheath. The dorsal petal is ovate, whereas the lateral petals are shorter and rounded. The lip is three-lobed. The central lobe is obovate, 2 cm wide and divided at the tip, and the lateral lobes are linear-lanceolate. Stamen filaments have white, pointed appendages.
Illustration from Curtis's Botanical Magazine
Colour print of Roscoea purpurea after a watercolour by Christabel King (1994), taken from Curtis's Botanical Magazine (Image: Christabel King)
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 two hundred 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.
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Roscoea purpurea is cultivated as an ornamental. In northern India the fleshy roots are traditionally used for making a tonic to treat malaria. In Nepal they are boiled and eaten and also used in traditional veterinary medicine.
At Kew the Roscoea collection is repotted in late January to early February, in a moisture-retentive but well-drained compost, before the pots are plunged into sand in an outdoor frame. The pots are watered in, then only the sand is kept damp until the first signs of growth in spring. Once in full growth, they are kept well watered and shaded on hot days. Between the time the foliage dies back in autumn and repotting takes place in winter, both pots and plunge sand are kept completely dry.
Most species are propagated readily from offsets, but they are also easy to propagate from seed, although this does mean it takes longer before they reach flowering size.
This species at Kew
The first Kew collection of the striking red-flowered form was made by the Kew botanist William Baker on the Oxford University Ganesh Himal expedition in 1992, and this collection is still grown at Kew.
Alcohol-preserved specimens of Roscoea 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, including images, can be seen online in the Herbarium Catalogue.
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Although native to the tropics, this species has naturalized in UK domestic gardens by hitchhiking in compost or rich soil used for potted plants.
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