Roscoea
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Roscoea is a genus of perennial plants of the family Zingiberaceae. They are native to China and Himalayas and related to a ginger plant. The Roscoea flowers resemble an orchid. There are 18 species in this genus.[1]
| Standard Cyclopedia of Horticulture |
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Roscoea (named after Wm. Roscoe, 1753-1831). Zingiberaceae. Half-hardy perennial herbs often grown in the warmhouse, but also used for border planting. Roots thick, fleshy, and fascicled: lvs. lanceolate or oblong: infl. in terminal spikes; bracts persistent, 1-fld.; fls. purple, blue, or yellow; calyx long, tubular, slit down one side; corolla-tube slender, lateral segms. spreading, upper broad, cucullate, erect; lateral staminoides oblanceolate, petaloid, erect, lip large, cuneate, deflexed, 2-cleft or emarginate; ovary 3-celled: caps, cylindric or clavate.—About 15 species, Himalaya region and China. Roscoeas thrive in light turfy loam and are prop. by division. R. purpurea is the species best known in cultivation.
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Merge this info
Info from: Robert Hamilton
Roscoea is a small genus of late spring / summer growing plants of the ginger family , Zingiberacea. They have a growing point from which a cluster of thickened roots decend , somewhat like a Dahlia but in minature form. The leaves are reminiscent of a minature sweet corn, with flower at the apex , which to my eye is somewhat orchid like (thinking Masdevallia) with one large decending petal and several smaller petals above and beside the main petal. They originate mainly from India, Nepal and China.
In Tasmania they need partial to full shade and additional summer watering to grow well. They tolerate moisture when dormant and do equally well in the ground or pots. For those in cooler climates they are said to be outdoors hardy in Britian.
They germinate easily from seed . When sown in late summer germination usually occurs in autumn, while seed sown in early spring emerges with the timing of mature plants. Some species tend to seed around a bit including into adjacent pots. Mature plants can be divided in winter.
The biggest problem with Roscoea is identification of the species. Several species have been perpetually misnamed . The best treatment
I have read of the genus is by Richard Wilford from RBG Kew in the March 1999 quarterly bulletin of the Alpine Garden Society.
I grow the following but cannot absolutely guarantee the identity of my species.They range from 5cm (2 inches ) to 30cm (12 inches) tall.
Roscoea alpina - a small species with mauve to purple flowers which is easily grown and seeds freely.
Roscoea australis - small purple / mauve flowers similar to alpina but has broader and shorter leaves.
Roscoea auriculata - this plant has been distributed in Australia as
Roscoea purpurea or purpurea procera. It grows well but does not tolerate too much sun - I often find it wilting after a warm day, but it recovers with a good water in the evening. Flowers are a deep violet-purple. The auriculata refers to the ear shaped first leaf on the pseudostem.
Roscoea cautleoides - in its yellow form it is easily recognised but purple and white forms are becoming available with the explosion of new plant material from China. I find it needs help to set seed and the seeds are difficult to recover from amongst the bracts.
Roscoea humeana - this has a large hooded dorsal petal , larger than the labellum giving it a distinct appearance. It is commonly purple , but yellow , cream and white forms do occur. My seedlings are reasonably new but it seems to be a vigorous grower.
Roscoea purpurea - this is the type species which was described in 1806. Flowers are pale purple or mauve. It is said to be the most vigorous species growing up to 50cm ( 20 inches ) tall.
I have kept my original plant in a pot and have not found it to be this vigorous, but it has quite broad and heavy leaves. I intend to plant in the garden next spring as I now have my own seedlings . To illustrate the difficulties with identification I have now almost convinced myself that my plant is R capitata - my plant has flowers of rich deep purple on a long peduncle- seen the image. A red form of R purpurea was discovered in 1994 a unique colour in the genus.
Roscoea scillifolia- this is the smallest of the genus growing little more than a few cm tall. The flowers can be pink , purple or white. I have a pink form whose flowers are fairly fleeting. It seeds around quite freely and appears last of the species I grow - in flower at present in early February.
Roscoea tibetica - my plants are still unflowered seedlings. It is another small species with typically dark purple flowers , which can also range from violet to mauve , rose or white. The photograph in the AGS article shows horizontal lateral petals making it look more like a typical orchid flower.
The following list of species I have not grown is taken from the AGS article.
Roscoea Beesiana - a vigorous hybrid between auriculata and cautleoides with variable amounts of violet striping.
Roscoea capitata -rich deep purple
Roscoea forrestii- small , yellow or purple flowers.
Roscoea ganeshensis - a recently discovered species from Nepal. Pale purple flowers , with narrow dorsal petal is a paler colour than the rest of the flower.
Roscoea praecox - a new species collected on the Alpine Garden Society China Expedition. Purple with up to six white lines on the base of the labellum.
Roscoea schneideriana - dorsal is pale pinkish -purple with rest of the flower a darker violet-purple.
Roscoea tumjensis - dark purple similar to humeana with labellum larger than the dorsal petal.
Roscoea wardii - purple flowers.
I have posted some Roscoea to the wiki which I have dragged out of my archives - none are photographic masterpieces but give some idea of the species available.
http://www.ibiblio.org/pbs/pbswiki/index.php/Roscoea
Roscoea alpina - sorry I didnt remove the dead flower.
Roscoea auriculata makes an attractive small clump.
Roscoea capitata - obtained as seed as R purpurea but my =93homework=94= makes me think this is the correct name - in reality it is a rich deep purple.
Roscoea cautleoides- the colour is a little washed out on this image Roscoea humeana -the split dorsal petal is not a normal feature but the image illustrates its =93fuller =93 flower.
Roscoea ?Beesiana- this is Lyn=92s image of a plant she obtained as = R cautleoides which we think may be the hybrid R Beesiana, said to have variable violet striping.
Cultivation
Propagation
Pests and diseases
Varieties
Some species:
Gallery
photo 1
photo 2
photo 3
References
- ↑ "Botanica. The Illustrated AZ of over 10000 garden plants and how to cultivate them", p. 801 Könemann, 2004. ISBN 3-8331-1253-0
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963
