Saxifraga xarendsii group (Hybr.) (complex hybrids involving S. exarata Villars, S. hypnoides, S. rosacea and other species) – A very rare and probably mostly ephemeral escape from or relic of cultivation, or merely a temporarily established throw-out. In one locality, however, at the Reinhardstein castle in Waimes, it has been known at least since 1950 (confirmed in 2015). Formerly also documented from ruins of the former abbey in Lobbes (1864). In recent years also seen for instance in Chimay (2012).
This complex of cultivars is morphologically very similar to other so-called mossy saxifrages, including S. hypnoides and S. rosacea, two of its putative parents that are (possibly) native in Belgium. However, petal colour is usually pinkish or reddish in these cultivars, whereas it is white in the native species.
Saxifraga xarendsii is an invalid name. Its precise parentage is uncertain. In addition to the species mentioned above, Jäger & al. (2008) also suggest S. cespitosa L., S. moschata Wulfen and S. pedemontana All. as putative parental species. Further useful information about this assemblage is provided by Harding (1970), Köhlein (1984) and Harding (1992).
Selected literature
Harding W. (1970) Saxifrages. The genus Saxifraga in the wild and in cultivation.
Harding W. (1992) Saxifrages. A gardeners’ guide to the genus.
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.
Köhlein F. (1984) Saxifrages and related genera.
McGregor M. (1992) Mossy saxifrages: a first encounter. J. Saxifrage Group 2: 9-32.
Thoen D. (1999) La flore du bassin hydrographique de la Semois. Observations chorologiques et écologiques sur la période 1995-1997. Adoxa 22: 11-20.
Webb D.A. (1951) The mossy saxifrages of the British Isles. Watsonia 2: 22-29. [available online at: http://www.watsonia.org.uk/html/watsonia_2.html#p22.pdf]