Rodgersia is a small genus of robust herbaceous perennials in the family Saxifragaceae (order Saxifragales), native to east Asia. The genus comprises around five to six accepted species, all originating from China, Tibet, Nepal, and — in the case of R. podophylla — the Japanese island of Honshū and Korea.
Plants grow from thick rhizomes that spread just below the soil surface. Most species are clump-forming, though R. nepalensis and some forms of R. podophylla can spread to cover large areas once established. Leaf stems typically reach about one metre in height, and the large compound leaves — particularly those of R. podophylla — can spread to a similar width, giving the plants a bold, architectural character. In good light, the foliage often develops a distinctive bronze or copper hue in spring, deepening to coppery-brown tones in autumn. The flowering stems rise above the leaves and carry showy panicles; although the flowers lack true petals, they are colourful in white, cream, pink, or red (greenish-yellow in R. nepalensis). Seed heads of many R. pinnata forms become claret-coloured and deepen through winter.
The genus was described by American botanist Asa Gray in 1885 and named in honour of US Admiral John Rodgers, who led the expedition during which R. podophylla was first collected in the 1850s. Notable species include R. aesculifolia (discovered by Father Armand David in 1869), R. pinnata (also collected by David in Yunnan in 1883), and R. sambucifolia (collected by Ernest Wilson in 1904). The garden plant Astilboides tabularis was formerly placed in Rodgersia.
Etymology
The genus was named by American taxonomist Asa Gray in 1885 in honour of US Admiral John Rodgers, commander of the naval expedition during which Rodgersia podophylla was first collected, in the 1850s.
Distribution
Rodgersia podophylla is native to Honshū, Japan, and to Korea; all other species are found in China, Tibet, and Nepal, with the geographical ranges of most species overlapping. In their native habitats, rodgersias grow along streamsides and in shady, moist woodland.
Ecology
Rodgersias grow naturally by streams and in shady moist woodland across east Asia. They spread via thick rhizomes just below the soil surface and are hardy to USDA Zone 5, though new spring growth can be damaged by late frosts. Their large leaves make them susceptible to sun- and wind-scorch in exposed positions.
Cultivation
Rodgersias thrive in moist, humus-rich soil that never dries out but is not waterlogged. They will grow in full sun if moisture is consistently available, but perform best in partial shade where foliage colour and leaf condition are at their finest. They are hardy down to Zone 5.
History
The genus was established by Asa Gray in 1885. R. podophylla reached the United States by 1871 and was flowering in the Imperial Botanical Garden at Saint Petersburg the same year; seed sent to British nursery Veitch & Sons in 1878 produced the first flowering plants in cultivation in the UK. R. aesculifolia was discovered by Father Armand David in 1869, and R. pinnata by the same collector in Yunnan in 1883, first flowering in the UK in 1902. R. sambucifolia was collected by Ernest Wilson in 1904 in Yalung, China.
Taxonomy Notes
A 1994 revision by Pan Jin-tang recognised five distinct species in the genus. Astilboides tabularis, a popular garden plant, was formerly placed in Rodgersia but is now treated as a separate genus. Rodgersia henrici, once considered distinct, has been reduced to a variety of R. aesculifolia. GBIF currently lists two accepted species in its backbone.
