Rodgersia
Encyclopedia
Rodgersia is a genus of flowering plant
s in the Saxifragaceae
family. Rodgersia are herbaceous perennials originating from east Asia
.
Jin-tang further described the varieties R. aesculifolia var. aesculifolia, R. aesculifolia var.henrici (Franchet) C.Y.Wu, R. sambucifolia Hemsl.var. estrigosa J.T.Pan, R. pinnata Franch.var.pinnata and R. pinnata var.strigosa J.T.Pan.
and was flowering in the Imperial Botanical Garden at St. Petersburgh and in 1878, seed brought back to a British nursery, Veitch & Sons, produced flowering plants.
R.aesculifolia was discovered by Abbe, later Pere, David
in 1869.
R. pinnata, was also discovered by Abbe David, in China's Yunnan province, in 1883. It first flowered in the UK in 1902. R. sambucifolia was discovered by Ernest Wilson 1904 in Yalung, China.
R. nepalensis was not identified until in 1966 in the UK from a collection by Peter Schilling
who made a second collection of seeds of this species . There are distinct differences between the plants raised from these two collections whose numbers are EMAK 713/901 and ED2879.
R. henrici which was initially thought to be an astilbe
was collected by Prince Henri d'Orleans in 1895 but this has recently been reduced to a variety of R. aesculifolia.
In older literature there is mention of R. purdomii named after William Purdom who collected in China in around 1910. The herbarium specimen of a plant raised from that seed, at Kew
, identifies it as R. aesculifolia.
and to Korea
. All the other species are found in China
, Tibet
, and Nepal
. The geographical ranges of all but R. nepalensis overlap each other.
In their native habitats they grow by streams and in shady moist woodland. In cultivation they thrive in soil that never dries out but is not waterlogged. They will grow in sun under these conditions in good humus rich soil but they are susceptible to sun- and wind-scorch. They are hardy down to Zone 5 but their new growths in the spring can be damaged by late frosts.
The thick rhizomes spread just under surface of the soil. Three of the species are clump forming, whereas R. nepalensis and some forms of R. podophylla can cover large areas quite quickly once they are established.
The strong leaf stems grow to an average height of about one metre but this depends on the variety and growing conditions. The spread of the compound leaves, especially of R. podophylla, can also be up to one metre making them architectural plants in cultivation. The flowering stems rise above the foliage and the panicle
s of flowers, although lacking true petals, are spectacular and colourful being white, cream, pink or red except in R. nepalensis which are greeny yellow.
The leaves of many varieties are attractive in the Spring when, grown in good light, they have a bronze or copper hue.This is especially beautiful in the Purdomi group of R. aesculifolia which keep a metallic sheen into early summer. In the autumn(fall), the leaves turn attractive shades of coppery-brown.
The seed heads are also attractive, those of many R. pinnata are claret coloured which deepens as winter progresses.
There are two forms of R. podophylla, one which has tough leathery leaves which are often bronze in the spring and autumn, and a thinner leaved form which remains a light green colour.
R. podophylla is often very shy at flowering, but can cover large areas by means of its spreading rhizomes. The flowers are white, the sepals ageing to green as do the ovaries.
Recently, R. aesculifolia (chestnut-leaved) has been divided into three distinct taxa.
All the veins in var. henrici are sunken, giving the top surface of the leaflets a quilted effect and on the underside, all the veins are prominent. The leaflets of var.aesculifolia have an almost smooth upper surface and only the main veins are prominent on the underside. The normal number of leaflets for var. henrici is 7 - 9 ; for var. aesculifolia it is 6 - 7.Pan (1994) provides a key that separates R.aesculifolia var. aesculifolia from var. henrici. This key states that var. henrici has more glandular hairs on the ventral surface of its sepals than var. aesculifolia and that the arcuate (curved) sepal veins meet at the tips whereas they do not in var. aesculifolia .
From a gardener's point of view, the general differences in the non-microscopic features of the plants are sufficiently diagnostic.
The leaves are pinnate and remain green throughout their life. The number of pairs of leaflets varies with the age of the plant and habitat. It is the smallest, in stature, of all of the species having foliage and flower spikes around 500mm tall. The small white flowers rapidly age to browny green.
The two varieties established by Pan are distinguished by microscopic features.
(Sambucifolia; having leaves like Sambucus, the Elder tree)
Rarely are the leaflets arranged in true pinnate form with evenly spaced leaflets.They vary from pseudo-pinnate, when the leaflets can be bunched 2 to 5 at the petiole and 3 at the apex with varying numbers of pairs of leaflets between with varying lengths of rachis, to plants where the rachis
is so compressed as to need very close inspection to ascertain that it is not palmate.
The size of the individual obovate-lanceolate leaflets ranges from 20mm long x 10mm wide to double those measurements depending on variety and growing conditions. The height of the leaves may exceed one metre and that of the inflorescence, one and a half metres.
The flowers can be white, palest pink to deep claret colour and the subsequent seeds heads range from green through to deep mahogany.
There are many cultivars, R.pinnata is very variable in all its aspects and readily hybridises with both R.podophylla and R.aesculifolia.
As with R.sambucifolia , the two varieties established by Pan are distinguished by microscopic features.
The sepals of EMAK are pale green, those of ED pale yellow. The flower colour distinguishes R.nepalensis from all other Rodgersia
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s in the Saxifragaceae
Saxifragaceae
Saxifragaceae is a plant family with about 460 known species in 36 genera. In Europe there are 12 genera.The flowers are hermaphroditic and actinomorphic...
family. Rodgersia are herbaceous perennials originating from east Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
.
Taxonomy
The review of the genus by Pan Jin-tang, in 1994 recognises five distinct species.- R. aesculifolia
- R. henrici
- R. pinnata
- R. podophyllaRodgersia podophyllaRodgersia podophylla is a plant in the Saxifragaceae family native to Asia. It is extensively grown for ornamental use in gardens where it prefers damp shady positions on neutral to acid soils.-External links:*...
- R. sambucifolia
Jin-tang further described the varieties R. aesculifolia var. aesculifolia, R. aesculifolia var.henrici (Franchet) C.Y.Wu, R. sambucifolia Hemsl.var. estrigosa J.T.Pan, R. pinnata Franch.var.pinnata and R. pinnata var.strigosa J.T.Pan.
History of discovery
The genus was designated by the American taxonomist, A.Gray, in 1885, who named it after the US Admiral, John Rodgers, commander of the expedition in which R. podophylla was discovered in the 1850s. By 1871, R. podophylla was present in the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and was flowering in the Imperial Botanical Garden at St. Petersburgh and in 1878, seed brought back to a British nursery, Veitch & Sons, produced flowering plants.
R.aesculifolia was discovered by Abbe, later Pere, David
Armand David
Father Armand David was a Lazarist missionary Catholic priest as well as a zoologist and a botanist.-General Biography:...
in 1869.
R. pinnata, was also discovered by Abbe David, in China's Yunnan province, in 1883. It first flowered in the UK in 1902. R. sambucifolia was discovered by Ernest Wilson 1904 in Yalung, China.
R. nepalensis was not identified until in 1966 in the UK from a collection by Peter Schilling
Peter Schilling
Peter Schilling is a German synthpop musician whose songs often feature science-fiction themes...
who made a second collection of seeds of this species . There are distinct differences between the plants raised from these two collections whose numbers are EMAK 713/901 and ED2879.
R. henrici which was initially thought to be an astilbe
Astilbe
Astilbe is a genus of 18 species of perennial, herbaceous flowering plants, within the family Saxifragaceae. Some species are commonly known as False Goat's Beard, and False Spirea...
was collected by Prince Henri d'Orleans in 1895 but this has recently been reduced to a variety of R. aesculifolia.
In older literature there is mention of R. purdomii named after William Purdom who collected in China in around 1910. The herbarium specimen of a plant raised from that seed, at Kew
Royal Botanic Gardens, Kew
The Royal Botanic Gardens, Kew, usually referred to as Kew Gardens, is 121 hectares of gardens and botanical glasshouses between Richmond and Kew in southwest London, England. "The Royal Botanic Gardens, Kew" and the brand name "Kew" are also used as umbrella terms for the institution that runs...
, identifies it as R. aesculifolia.
Habitat and Description
R. podophylla is native to the island of Honshū in JapanJapan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and to Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...
. All the other species are found in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Tibet
Tibet
Tibet is a plateau region in Asia, north-east of the Himalayas. It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpas, Qiang, and Lhobas, and is now also inhabited by considerable numbers of Han and Hui people...
, and Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
. The geographical ranges of all but R. nepalensis overlap each other.
In their native habitats they grow by streams and in shady moist woodland. In cultivation they thrive in soil that never dries out but is not waterlogged. They will grow in sun under these conditions in good humus rich soil but they are susceptible to sun- and wind-scorch. They are hardy down to Zone 5 but their new growths in the spring can be damaged by late frosts.
The thick rhizomes spread just under surface of the soil. Three of the species are clump forming, whereas R. nepalensis and some forms of R. podophylla can cover large areas quite quickly once they are established.
The strong leaf stems grow to an average height of about one metre but this depends on the variety and growing conditions. The spread of the compound leaves, especially of R. podophylla, can also be up to one metre making them architectural plants in cultivation. The flowering stems rise above the foliage and the panicle
Panicle
A panicle is a compound raceme, a loose, much-branched indeterminate inflorescence with pedicellate flowers attached along the secondary branches; in other words, a branched cluster of flowers in which the branches are racemes....
s of flowers, although lacking true petals, are spectacular and colourful being white, cream, pink or red except in R. nepalensis which are greeny yellow.
The leaves of many varieties are attractive in the Spring when, grown in good light, they have a bronze or copper hue.This is especially beautiful in the Purdomi group of R. aesculifolia which keep a metallic sheen into early summer. In the autumn(fall), the leaves turn attractive shades of coppery-brown.
The seed heads are also attractive, those of many R. pinnata are claret coloured which deepens as winter progresses.
R. podophylla
The leaves of R. podophylla, Gray (diploid 2n=30) are palmate. The individual leaflets, from 5 to 7 in number, have between 3 to 5 drip tips at their angular apices. The leaflets resemble a duck's webbed foot (Gk.podos a foot and phyllon a leaf) and this is sufficient to identify R. podophylla from all the other species.There are two forms of R. podophylla, one which has tough leathery leaves which are often bronze in the spring and autumn, and a thinner leaved form which remains a light green colour.
R. podophylla is often very shy at flowering, but can cover large areas by means of its spreading rhizomes. The flowers are white, the sepals ageing to green as do the ovaries.
R. aesculifolia
In R. aesculifolia, Batalin (tetraploid 2n=60") the leaves are symmetrically palmate radiating from a central point most often without petioles.They are obvate with acute apices and coarsely serrated.Recently, R. aesculifolia (chestnut-leaved) has been divided into three distinct taxa.
- White flowered.
This has small flowers, 2 - 8mm in diameter. The green, white or yellowish buds open to white flowers that go green with age. It has green leaves throughout the growing season and airy inflorescences with curled flower clusters. - Purdomii taxon.
This also has small flowers 2 - 8mm in diameter but the flower buds are pink opening to sepals tinged or tipped pink turning white, the flowers ageing green. The young leaves are copper or bronze in colour and the older leaves retain a metallic shean. The inflorescences have an airy appearance as in taxon 1. - Henrici taxon.
This has large flowers 8 - 18mm in diameter, a major difference with the other two taxa. The bright pink sepals and ovaries get progressively deeper in colour as they age and remain claret-coloured through autumn. The inflorescences have nothing "airy" about them but are solid-looking, broad based with flower clusters that have almost flat tops with their undersides clearly visible when viewed from the side. They form tiers as in a multiple wedding cake and the flowers are closely packed along the pedicels. The texture of the leaf surface of var. henrici is firm and there is no tendency to deflect downwards from the mid-vein or at the apex, as in the soft-textured var. aesculifolia.
All the veins in var. henrici are sunken, giving the top surface of the leaflets a quilted effect and on the underside, all the veins are prominent. The leaflets of var.aesculifolia have an almost smooth upper surface and only the main veins are prominent on the underside. The normal number of leaflets for var. henrici is 7 - 9 ; for var. aesculifolia it is 6 - 7.Pan (1994) provides a key that separates R.aesculifolia var. aesculifolia from var. henrici. This key states that var. henrici has more glandular hairs on the ventral surface of its sepals than var. aesculifolia and that the arcuate (curved) sepal veins meet at the tips whereas they do not in var. aesculifolia .
From a gardener's point of view, the general differences in the non-microscopic features of the plants are sufficiently diagnostic.
R. sambucifolia
R. sambucifolia, Hemsley (tetraploid 2n=60)The leaves are pinnate and remain green throughout their life. The number of pairs of leaflets varies with the age of the plant and habitat. It is the smallest, in stature, of all of the species having foliage and flower spikes around 500mm tall. The small white flowers rapidly age to browny green.
The two varieties established by Pan are distinguished by microscopic features.
(Sambucifolia; having leaves like Sambucus, the Elder tree)
R. pinnata
R. pinnata, Franchet (tetraploid 2n=60) has the most diverse leaf form of any of the Rodgersia and this leads to mis-identification and mis-labelling in horticulture.Rarely are the leaflets arranged in true pinnate form with evenly spaced leaflets.They vary from pseudo-pinnate, when the leaflets can be bunched 2 to 5 at the petiole and 3 at the apex with varying numbers of pairs of leaflets between with varying lengths of rachis, to plants where the rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...
is so compressed as to need very close inspection to ascertain that it is not palmate.
The size of the individual obovate-lanceolate leaflets ranges from 20mm long x 10mm wide to double those measurements depending on variety and growing conditions. The height of the leaves may exceed one metre and that of the inflorescence, one and a half metres.
The flowers can be white, palest pink to deep claret colour and the subsequent seeds heads range from green through to deep mahogany.
There are many cultivars, R.pinnata is very variable in all its aspects and readily hybridises with both R.podophylla and R.aesculifolia.
As with R.sambucifolia , the two varieties established by Pan are distinguished by microscopic features.
R. nepalensis
R. nepalensis , T.A.Cope ex Cullen has a truly pinnate leaf, blue-green in EMAK 713, yellowy-green in ED2879. The individual leaflet are about 15mm long and 5mm wide with markedly serrated edges, tipped red brown in EMAK, yellow in ED.The sepals of EMAK are pale green, those of ED pale yellow. The flower colour distinguishes R.nepalensis from all other Rodgersia