One of the less commonly found plants for shaded places is of the genus Roscoea. It is one of the few members of the Family Zingiberaceae (the ginger family), which can grow outside tropical or subtropical climates, because it is a native of high altitudes in Sichuan and Yunnan in China. The genus is named after William Roscoe, an abolitionist, friend and ally of Hulls famous son, William Wilberforce. Roscoe was a poet, historian, lawyer, banker, MP, Unitarian a true son of Liverpool, and a botanist who helped to establish Liverpools botanic garden.
Roscoea is a tuberous perennial. Its eye-catching flowers appear in mid-summer. Roscoea cautleyoides AGM has hooded, clear pale yellow orchid-like flowers in June to August, height 30 cm. Flowers appear within a week or two of the green stems sheathed by alternate glossy foliage. Plant tubers deeply 15 cm (6 in) in Feb to March in moist well-drained soil in a sheltered position since they are only borderline hardy, though in my garden they have given no problems over five or more years. As a precaution you could apply a deep winter mulch. To propagate, divide plants in March to April.
Of several cultivars, R. cautleyoides 'Kew Beauty' AGM is a more robust plant with larger yellow flowers than the species. R. cautleyoides 'Purple Giant' flowers in May and is considered the purple equivalent of 'Kew Beauty', with large blooms. There are many other cultivars. The celebrated William Robinson described it as possessing ... a beauty quite apart. Roscoea purpurea also has several cultivars. Bob Brown recommends the later flowering R. purpurea 'Brown Peacock' large soft violet-purple flowers in August - September, large dark red-black flushed foliage from a massive thick stem, 55 cm. It is easy to cultivate. Similar is R. purpurea 'Nico', with exceptionally large deep purple flowers in July - September, deep red-flushed and lined dark green foliage, thick reddish stems, a compact plant only 20 cm high, best grown in partial shade. The hooded, 6 cm blooms are purple or occasionally white and bi-colour.
Roscoea procera (syn. Roscoea purpurea var. procera) is of slender habit with deep green leaves up to 25 cm long which are lance-shaped. The flowers bloom in early and midsummer, purple or white bi-coloured.
Roscoea 'Beesiana Alba' 35-40 cm has narrow, upright foliage that resembles young corn stalks. They emerge late in the spring and begin blooming in mid to late summer. The orchid-like flowers are pale yellow with highly variable purple streaks through the petals. It is a hybrid between R. auriculata and R. cautleyoides.
I have not yet seen many other varieties: R. alpina, the true species (not scillifolia which is often offered) has large purple flowers in June, excellent for a shady rock garden, 6" high. R. auriculata is a midsummer flowering species with uniform flowers of violet-purple. R. humeana AGM is a May flowering, stocky plant with large claret-purple flowers (with several named cultivarsyellow, white and plum coloured). R. tibetica is a rare short 6 tall variety with two-toned flowers of magenta purple and white lower lip.
If you want a plant of elegant beauty and something a little bit different, try one of Roscoea.
First published in the East Yorkshire Group Newsletter, November 2007
and subsequently in Cornucopia Issue 25.
© Copyright for this article: JMS Pearce
This article was taken from a copy of Cornucopia that was published in 2010. You could be reading these articles as they are published to a national audience, by subscribing to Cornucopia.