Rodgersia A. Gray
Rodgersia is a genus with five species, all confined to eastern Asia and the Himalayas. Four species occur in China (Pan & Cullen 2001). All these are also grown as ornamentals, although in the horticultural trade pure species seem to be rare (Jäger & al. 2008).
Two closely similar species or cultivars of them have been recorded in Belgium, either as escapes from or relics of cultivation. They mostly reproduce vegetatively, seeds are rarely produced (Stace 2010).
Additional useful information on the genus is provided by Rodgersia - Sichtung at: http://www.staudensichtung.de/rodgersia.html.
1 Leaflets entire at apex, sparsely glandular hairy on upper leaf surface === Rodgersia aesculifolia
Leaflets 3(–5)-lobed at apex, glabrous on upper leaf surface === R. podophylla
Literature
Akiyama S., Ohba H. & Wakabayashi M. (1990) Notes on the interspecific relationship in the genus Rodgersia (Saxifragaceae). J. Jap. Bot. 65(11): 328-338.
Beckett K.A. (1978) Rodgersia. Bull. Hardy Pl. Soc. 5(4): 62-63.
Cullen J. (1975) Taxonomic notes on the genus Rodgersia. Notes Roy. Bot. Gard. Edinburgh 34(1): 113-123.
Cullen J. (1995) Rodgersia. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 4. Cambridge University Press, Cambridge: 248.
Dunlop G. (2001) William Purdom's Rodgersia. New Plantsman 8(4): 218-223.
Jäger E.J., Ebel F., Hanelt P. & Müller G. (eds.) (2008) Rothmaler Band 5. Exkursionsflora von Deutschland. Krautige Zier- und Nutzpflanzen. Springer Verlag, Berlin: 880 p.
Lancaster R. (1993) Plants that should be better known: Rodgersia henrici. Garden (London) 118(6): 250-251.
Ma X., Sun W., Zhu W. & Sun H. (2017) Resolving the phylogenetic relationships and evolutionary history of the East Asian endemic genus Rodgersia (Saxifragaceae) using multilocus data. Perspectives in Plant Ecology, Evolution and Systematics 25: 20-28.
Pan J.T. (1994) Phylogeny classification and geographic distribution of Rodgersia Gray (in Chinese). Acta Phytotax. Sin. 32(4): 316-327.
Pan J. & Cullen J. (2001) Rodgersia. In: Wu Z.Y. & Raven P.H. (Eds.) Flora of China 8. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis: 272-274. [available online at: http://flora.huh.harvard.edu/china/PDF/PDF08/RODGERSIA.pdf ]
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Straley G.B. (1995) Rodgersias, jewels of saxifrages. Pac. Hort. 52(2): 31-35.