and Sempervivum are cultivated for rock gardens and for "green roofs". In particular, cultivars of the Madagascan Kalanchoe blossfeldiana, e.g. 'Florists kalanchoe' have achieved commercial success throughout the world, being popular Christmas decorative plants. The Haloragaceae aquatic genus Myriophyllum and the closely related Proserpinaca are cultivated for the commercial aquarium trade. Myriophyllum is also economically important for purification of water and as feed for pigs, ducks, and fish, and polishing wood. A number of Ribes (Grossulariaceae) are in commercial production, concentrated in Europe and the USSR from species native to those areas. R. nigrum (blackcurrant) was first cultivated in monastery gardens in Russia in the 11th century, and currant cultivation more generally later in Western Europe, R. uva-crispa (gooseberry) production began around 1700. The first colonists in N America began cultivating currants in the late 1700s. R. nigrum is the most important commercial currant crop, being produced in more than 23 countries, with the major centres being Russia (more than 63 thousand hectares), Poland, Germany, Scandinavia and the UK. An important source of Vitamin C, black currants are used in the manufacture of jam, fruit jelly, compote, syrup, juice and other drinks, including the cordial Ribena and the liqueur Cassis. Other commercial crops include R. rubrum (red currant). World Ribes crop production was over 750,000 tons in 2002, of which about 150,000 tons were gooseberries, and the largest group blackcurrants. See also List of Saxifragales families Notes References Bibliography Books Chapters (full text at ResearchGate) Historical Articles Angiosperms Eudicots Saxifragales APG Saxifragales families Paleontology Websites (see also Angiosperm Phylogeny Website) , see also IUCN Red List , in Flora of China online vol. 13 Images External links Angiosperm orders Taxa named by Friedrich von Berchtold Taxa named by Jan Svatopluk Presl hu:Kőtörőfüvek